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Everything You Need To Know About Red Light Therapy

Do you have a question about red light therapy, photobiomodulation or LLLT (they are all the same thing)?

Well this article is for you. I have spent weeks researching the literature on red light therapy and have created this comprehensive guide to answer every question you may have!

I've covered everything from the best wavelength to use, whether it's safe for your eyes, the difference between LEDs and laser and much, much more!

I have split the article into 3 categories:

  1. What You Need To Know About Red Light Therapy

  2. What You Need To Know About Using Red Light Therapy Devices

  3. What You Need To Know About Buying Red Light Therapy Devices

But please note:

  • This article is long! Over 15,000 words long. You can either read start to finish or:
  • Use the table of contents below, simply click the question that you want answered to skip ahead
  • Or use the 'find' feature in your browser to type in a keyword
  • If I have missed something, or you can't find the answer to your question, please post a comment in the comments section and I'll do my best to answer it.
  • Also - some of the links within this article are affiliate links, please read this for more info.

Finally, if you already know enough about red light therapy, and just want some advice on buying the right device, I have put together this simple one page Red Light Therapy Buyers Guide. Just click HERE to access it. 

All Your Red Light Therapy Questions Answered:

Click the question to jump to the answer below.

What You Need To Know About Red Light Therapy

What You Need To Know About Using Red Light Therapy Devices

What You Need To Know About Buying Red Light Therapy Devices



What You Need To Know About Red Light Therapy 

  • What is red light therapy? 

Red light therapy, also referred to as Low Level Laser Therapy (LLLT) or photobiomodulation - is the act of using red light (or near infrared light) for beneficial properties on the body.

These beneficial properties are outlined in detail below, but red light (in the proper intensity and dose) has a therapeutic or healing effect on the tissue and body.

Red light therapy may involve someone using a laser that emits light in red light spectrum onto an injured body part, or a red light LED shown on the body as practical examples.


  • How is Red Light Therapy different to light from the sun or light bulbs?

Research has show that light in the red and near-infrared spectrum has a lot of benefits on the body. This light typically ranges from 620 nanometers (nm) in length, until to around 1000nm in length. 

These specific wavelengths penetrate very deep into the bodily tissues, and are also absorbed very well by the body.

This 600-1000nm light range makes up a very small slice of the electromagnetic spectrum as seen below:

In fact, it only comprises a small amount of the visible light spectrum we see from our naked eye.

Light sources such as the sun and common lightbulbs emit light in all spectrums of visible light - hence the name 'full spectrum light' and this is also why a Red Light Therapy device such as the Joovv panel will emit a red glow, whereas the sun will emit a white - yellow glow.


Note - it does need to be noted that near infrared light at around 800-1000nm is actually invisible to the naked eye, but is included in the red light therapy 'range' due to it's health benefits.

This is why the Joovv combo panel shown below appears to only have half of the LED lights working - in fact all are working, but only the 660nm red light LEDs are visible and the 850nm NIR lights are invisible.

  • How does red light therapy work?

If you have spent a bit of time on my site, you will know that light has numerous effects on the body.

For example:

Light does therefore not only function as a colour to illuminate your environment, but actually penetrates into the body, and subsequently has biological effects in that body. Consider the following image. It shows how deep different types of light wavelengths penetrate into the body:

Source – Saunaspace[2]

As you can see, red light has a deep penetration depth of compared to other forms of light, such as UV, blue, green, or the longer infrared wavelengths, meaning that the red light can reach deeper bodily tissues.

Other non-red wavelengths cannot reach that deep, and cannot affect the underlying tissue in the way that red light therapy does.

The deep tissue penetration also means that red light can have systemic effect on the human body, instead of the biological effects remaining localized in one specific area.

The reason for the systemic effects, is due to red lights ability to stimulate ATP production.

This quote from the paper titled Low-Level Laser Therapy for Fat Layer Reduction: A Comprehensive Review states:

The mechanism is based on absorption of red and near infrared photons by chromophores in the mitochondria (particularly cytochrome c oxidase), leading to increases of mitochondrial membrane potential, oxygen consumption, adenosine triphosphate (ATP), and a transient increase in reactive oxygen species (ROS).

A reader of mine simplfied this paragraph with the following comment:

It's the energy of the photon that's being utilize by the body.  Just as a plant uses light energy to generate complex molecules via chlorophyl, our own chromophores utilize the energy of the photons to do much the same, just for a different set of reasons: changing membrane potential, enhancing oxygen utilization, generating ATP etc

Because Red Light Therapy devices (and the LEDs often used in them) can be can made in such a way that they emit very specific light wavelengths, such as 630nm or 670nm, these LEDs have other advantages. Red light therapy devices aims to affect the mitochondria throughout the body. Mitochondria are the energy producing units of our cells. Improving mitochondrial function will improve the overall health of your body.

Not all wavelengths of red and infrared light are optimally absorbed by the mitochondria. By targeting the LEDs towards a few very therapeutic wavelengths, maximal absorption is accomplished.

Therefore, if you were to choose wavelengths that are not optimal,  the energy would be mostly wasted. Traditional bulbs such as incandescent or halogen use a lot of these intermediary wavelengths that do not have any proven therapeutic effects, because they do not emit enough light at the very specific wavelength peaks.

If you really want to geek out on the technical explanation behind how red light therapy works, check out THIS article and also THIS.

  • Does red light therapy work?

Yes! It has even been approved by the FDA!

There are 100's, maybe even 1000's of peer reviewed published studies showing the benefits of red light therapy.

I will not list them all here as it will be too much information, instead I highly recommend you look at my article titled The Fascinating Healing Properties of Red Light Therapy and references and links included in that article.

Another good article is 'Does Red Light Therapy Really Work?'

Alternatively, read about my own positive experiences using red light therapy in the article Powerful Results With The Red Light Therapy Device + EMF Levels Tested.

Or simply watch the video below:

And if this is all not enough, have a look at this 2011 research paper titled: 'Is light-emitting diode phototherapy (LED-LLLT) really effective?'

The researchers concluded that if the LED device has...

  1. the correct wavelength (more on this below)
  2. adequate photon intensity (power density - also covered below)
  3. adequate dose (measured in joules/cm2 - I cover this in detail below).

... then yes 'LED phototherapy does indeed work, and has many useful aspects in clinical practice for practitioners in many surgical specialities'.

For a great resource on red light therapy and the science showing how effective it is, I highly recommend reading this article - The Therapeutic Effects of Red and Near-Infrared Light (2017)

  • What are the benefits of red light therapy?

Numerous. Everything from decreased inflammation and pain, to rapid wound healing and increased skin collagen.

For a short list see below: 

  1. Lowered inflammation levels in the body.(1)
  2. Help treat problems like osteoarthritis, (joint) injuries, and excessive swelling.
  3. Red light therapy can improve hypothyroidism conditions.(2)
  4. Increased performance and cellular energy (3)
  5. Improved recovery times from training and injury (4,5)
  6. Increase testosterone and fertility (6)
  7. Improved skin health (7)
  8. Firmer skin (8)
  9. Improve oral health (9,10)
  10. Reverse Hair loss (11)

This is only a short list, for a comprehensive list on the benefits of red light therapy please read The Fascinating Healing Properties of Red Light Therapy.

You can also see the article 'What are the real benefits of light therapy?' posted at Joovv.com.


  • Is red light therapy safe?

Red Light Therapy doesn't use drugs, or surgery to boost your health. It simply uses light - light that is also found naturally in the sun.

Red light devices concentrate a particular wavelength of this natural light creating higher levels of 'natural light' than we would be exposed to while out in the sun for example.

To the best of my knowledge, there are no direct dangers to red light therapy if done using a quality device.

There may be indirect safety issues associated with red light therapy. The main issue being the potentially high levels of non-native electromagnetic fields that some devices emit.

I have tested the nnEMF output of a few panels and I was happy with the reading (see my findings HERE).

Also, be sure to read my section on potential side effects below.

  • Are there any side effects from using red light therapy devices?

The worst-case scenario qua side effects of red light therapy are headaches and exhaustion, because the body needs a lot of energy for the healing and mitochondria-building processes that red light therapy instantiates. Luckily, red light therapy can never result in a sunburn because no red light therapy device emits any UV.

Also, consider asking the company how high the emitted non-native electromagnetic frequencies of the device are. There have been reports by some users that their LED red light therapy devices emit high amounts of non-native electromagnetic frequencies (I have tested the Joovv panels and found their devices to be low in EMF).

Lastly, red light therapy should not be used late at night. On the one hand, red light therapy will never suppress melatonin levels like blue or green light does. But on the other hand, red light can suppress melatonin levels when the light intensity is sufficiently strong enough.(12)

The light intensity of many LED devices does achieve very high levels, because these devices are made to be used very close to the human body. You do not want your melatonin levels suppressed, because optimal melatonin levels are necessary for deep sleep.


  • Does Red Light Therapy speed up cancer growth if present?

The science is mixed. After reviewing a bunch of studies on red light therapy and it's affect on cancer and tumor growth, I found evidence supporting the use of RLT (32-36), and evidence showing that RLT can in-fact increase tumor cell proliferation (37-40).

One 2017 paper concluded:

"The findings of this study have led to the conclusion that LLLT increases cancer cell proliferation, depending on the power output level of the laser and the number of applications. In addition to the proliferation and mitotic activity of the cancer tissue cells, we concluded that LLLT, which is frequently used in dental practice, could activate precancerous cells or increase existing cancerous tissue." (37)

A detailed review on Photobiomodulation and cancer was published in the Photomedicine and Laser Surgery. The article in it's entirety has been republished for the public to read on the Joovv website titled Photobiomodulation and Cancer: What is the Truth?

You can read the review by clicking the link above. I have pasted the conclusion below for your convenience:

PBM (also referred to as Red Light Therapy) is becoming a well-established approach to mitigate or prevent the development of cancer-therapy associated side-effects, especially oral mucositis. The more intriguing question is not merely whether PBM is safe and effective in cancer patients, but whether PBM can play an active role in cancer treatment?

There are tantalizing reports that this may indeed be the case, but there are many questions still to be answered. The wide array of different devices and parameters that have been employed make this quite a complicated area. While the biphasic dose response is accepted in normal tissue, how it applies to malignant tissue is unclear. In some cases, it appears that a very high dose will create a cytotoxic level of ROS that can directly destroy the tumor.

In other cases, the main effect of PBM appears to stimulate the immune system, and a low dose may be more effective. If the aim is to stimulate the immune system, then is it best to directly irradiate the tumor, or to direct the light to the bone marrow, the lymphatic organs, or even the whole body? What can be concluded, is that now is perhaps the time to lose the fear of exacerbating cancer by shining light on it, and start to plan well-controlled clinical trials, even if these must necessarily be in advanced patients who have run out of options.

There is clearly a great number of new possibilities involving the combination of PBM with other forms of cancer therapy, that may allow us to take advantage of biochemical differences between cancer and normal cells to effectively work against the cancer.


It should also be noted that one study showed that less radiation is required when combined with PBM (41)

If you do suffer from cancer, or fear pre-cancerous cell growth, I highly recommend doing your own research on this topic before using red light therapy. 

A good starting place is THIS document - which lists all the studies done on photobiomodulation/red light therapy. Have a look through the section on 'Tumor Growth'.

Pay attention to the wavelengths used, and the dosages and also the frequency. Remember, there are many variables when it comes to red light - dosage amount, the wavelength, how often it is used, where it is applied etc.

If I had cancer, I would probably ere on the side of caution and avoid RLT until I had the all clear. 

As always, speak to your doctor. I am not a doctor and please don't take any medical advice from me. 

  • What wavelengths are used in red light therapy?

The typical range for red light therapy (RLT) devices is 600nm to 900nm.

Visible red light is between 620nm and 700nm as per the image below:

Source: Redlightman.com

Less than that and you have more of a orange light. Higher than that and you have invisible near-infrared light (NIR). Though NIR is commonly included as a 'red light therapy light'.

When looking at studies on RLT, we see benefits at 590nm, ranging all the way up to 1000nm.

Though it needs to be pointed out that majority of the studies show benefits from light in the 630-850nm light range. You can download a FREE guide to what wavelength is best for each health issue by clicking HERE.

Also, it should be noted that two of the top selling Red Light Therapy brands - Joovv and Red Light Man sell products that use wavelengths between 620nm and 850nm.

  • What is the difference between red light and near infrared light?

Near infrared light (NIR) is invisible to the naked eye and has a wavelength of ~700nm to ~1400nm.

Red light is visible to the naked eye and has a wavelength of ~600nm to 700nm.

Both types of light have been shown to be beneficial for healing and wellness (13). With NIR light below 950nm having the deepest skin penetration rates (2-3mm vs the 1-2mm found in red light and higher wavelength NIR light).

The team over at Joovv.com have put together a great explanation on the differences between the two types of light:

The major difference between these two wavelengths is their ability to penetrate skin tissue. Red light wavelengths at 660 nm are more quickly absorbed by the outer layers of your skin, which uses them to produce collagen, resulting in a host of benefits such as wrinkle reduction, enhanced skin tone, and the fading of scars and stretch marks. The red LEDs in our Joovv Lights deliver light at 660 nm, which has been proven to be beneficial across multiple clinical studies (some of which we’ve explored in other articles).

850 nm near infrared light generates virtually the same cellular response as 660 nm red light, but a greater percentage of the photons from near infrared light are able to reach deeper into your body. This equates to benefits like reduced joint pain and inflammation, enhanced muscle recovery, and nerve regeneration. These benefits of near infrared light at 850 nm are supported by a multitude of studies that we’ve covered in other articles.

An additional difference is that 850 nm LEDs produce a 30% higher irradiance using the same wattage. The combination of these factors leads to some impressive results!  


  • What is Polychromatic light therapy?

Polychromatic light therapy means multiple wavelengths of light are used at the same time.  Lots of RLT devices on the market have multiple wavelengths as standard. For example the Joovv Combo, and Novothor devices both use 660nm and 850nm light concurrently).

What are the pros' and cons of this?

Pros - multiple wavelength exposure (and the unique benefits that come with each).

Cons - often more expensive, and less exposure from a particular wavelength.


  • What is Cytochrome C Oxidase and what has red light therapy got to do with it?

For this question I reached out to Joovv for an explanation:

Cytochrome c oxidase (CCO), [is] the last enzyme in the respiratory electron chain transport of the mitochondria.

During the fourth phase of cellular respiration (oxidative phosphorylation), specific wavelengths of red and near infrared light break the bond between nitric oxide and CCO.

This allows oxygen to bind to NADH, restoring the normal pathway for hydrogen ions to create the electrochemical potential that produces ATP (cellular energy). A simple way to think of this process is that photons essentially charge your cellular batteries.

Activating cytochrome c oxidase is critically important when it comes to photobiomodulation.  With this in mind, let’s turn to the chart below, which depicts the activation of CCO at various wavelengths. As you can see, there are specific peaks of absorption in the mid-600 nm and mid-800 nm ranges. However, wavelengths in the 700-730 nm range, for example, have very little biological impact because of their inability to efficiently activate CCO. 


  • What wavelength should I go for when buying a red light device?

I cover this question in the 'buying a red light' section below. Alternatively you can us my Red Light Therapy Buyers Guide by clicking HERE.

But in a nutshell - it depends on your goal. As red light (in the 600-700nm range) doesn't penetrate deeply into the body, this wavelength may be better suited to someone wanting to improve skin health or help with surface wound healing.

If you want to focus on joint health, muscle health and full body health, then infrared light around 800-850nm may be your better option.

For a more detailed answer to this question, please download my free wavelength guide here.

Alternatively, do what I do, and use a red light device that emits both red light and NIR light! The Joovv combo panel does exactly this - with 50% of the light being 660nm and 50% of light being 850nm.

Finally, if you really want to geek out on the technical differences behind all the wavelengths, I highly recommend reading Red Light Therapy Optimum Wavelengths

And if you are confused about wattages, power intensities and irradiance when it comes to red light devices, be sure to read this great article - Measuring the Power of Light Therapy Device.


  • Whats so special about red LEDS for red light therapy?

Simple - they are an energy efficient way of emitting a very particular wavelength of light.

Other light bulbs such as incandescent bulbs or halogen bulbs emit a range of light - including reds, greens, yellows, blues and potentially invisible light such as UV or Infrared. 

Meaning you expend a lot of energy to receive only some (if any) of the therapeutic red light.

LEDs or Light Emitting Diodes - on the other hand can be manufactured to give out a precise wavelength of light - for example 660nm - without any other light being emitted.

This means the LEDS are converting more power into the beneficial light that red light therapy users are seeking. 
Plus there is less heat from LEDS - as heat can negatively impact the body or negate some of the benefits that red light has on the body (for example, Red light shown on testicles has been shown to improve testosterone levels, yet heating testicles can lower testosterone levels. For more on this please read Red Light ‘Triples Testicle Function’ Studies Show at RedLightMan.com


  • What is the difference between LEDs vs Lasers when it comes to Red Light Therapy?

I reached out to John from RedLightMan.com to help me with this question. Here is his response:

Lasers are good, but there’s no reason to believe they’re any better than LEDs for the purpose of light therapy. A photon is a photon, regardless of source – your cells don’t know the difference. The ‘coherent’ state of laser light is gone as soon as the light passes 0.1mm of skin.
Low level lasers will eventually be phased out in my opinion. I think they’ve only lasted this long because of the marketing appeal – ‘laser’ sounds clinical and interesting. Companies invest in research with them because they’re too expensive for patients to buy for using at home.
You can get nearly all of the same benefits from using LED light, and you can calculate dose and control strength just the same.

Also, the team at HeelSpurs.com have a great article on Red Light Therapy. In this article they explain the differences between lasers and LEDS:

There is no reason to believe that the coherent light from a laser is any better than LEDs, sunlight, or halogen lights. ( Unfortunately, authors of the last 10 years or so have twisted the historical meaning of LLLT to mean "low level LIGHT therapy" since lasers are fading away in importance in this area. )

Laser light might be more efficient since it may get through the skin more easily, but it does not penetrate more deeply once the light is beneath the skin, and cells do not know the difference: all photons are the same and the benefits are based on the action of each individual photon, not on bulk properties such as all the photons having the same polarity or coherency.

The word "laser" has a superior marketing appeal for companies because it sounds interesting and mysterious. It also costs a lot which means patients can't do it on their own.

These are the reasons there has been much more research in LLLT for healing than LEDs and halogens: companies and researchers have expected more profit. Light therapy is ancient and took on various new forms in the 1900's before lasers were invented.

At least since 1989 definitive statements were being made in journal articles that lasers are not needed. To quote the most recognized researcher in LLLT, Professor Tiina Karu: "An analysis of published clinical results from the point of view of various types of radiation sources does not lead to the conclusion that lasers have a higher therapeutic potential than LEDs. ...The coherent properties of light are not manifested when the beam interacts with a biotissue on the molecular level..... Successful use of LEDs in many areas of clinical practice also confirms this conclusion." (Biomedical Photonics Handbook, 2003). 


  • What is the difference between Red light therapy, photobiomodulation, LLLT and Light Therapy?

LLLT stands for 'Low Level Laser Therapy' - whereby lasers are used to emit a particular wavelength of light onto the body for it's healing and therapeutic benefits.

Red Light Therapy is all about using red and near infrared light for it's healing and therapeutic benefits. This light could come from LEDs, Lasers, incandescent bulbs or even the sun.

Photobiomodulation (PBM) is an another name for using low powered lasers or LED lights that emit a particular wavelength to help the body.

In essence, photobiomodulation is the same as Low Level Laser Therapy. 

And Red Light Therapy falls beneath these terms as it only looks at the red and infrared wavelengths of light.

Other names for PBM and LLLT may include: low-power laser therapy (LPLT), low-intensity laser therapy, cold laser therapy, low-energy laser therapy, bio-stim laser therapy, photo-biotherapy, monochromatic infrared light energy (MIRE) therapy and therapeutic laser.

Light Therapy - also know as phototherapy or heliotherapy - looks at light (of various colors from various sources) to help with medical conditions, sleep issues, jet lag, seasonal affective disorder and vitamin D deficiencies. 

  • Do red light devices emit UV light?

No. A red light therapy device should only emit light in the red and near-infrared range.

  • Can I use any red light to reap the benefits?


You need a light source that emits the correct wavelengths, and has a high enough power density to reap the benefits that red light therapy is known for.

I cover this question in more detail in the 'buying a red light' section below. Alternatively you can us my Red Light Therapy Buyers Guide by clicking HERE.

  • Does red light therapy tan you or burn the skin?

No. UV rays are needed to create sunburn in the skin. Red light devices do not emit UV rays.

  • Do you get Vitamin D from red light?

No. UV-B rays are needed to synthesis Vitamin D in the skin. Red Light devices do not emit UV rays.

If you are looking for a UV-B ray source, look into the Sperti Lamp, or of course the sun.

  • Whats the difference between red light and sunlight? Can't I get the benefits of red light therapy by standing in the sun?

There are two issues with using the sun as your source of red light for RLT, these are:

  1. Getting the right wavelength of light at the correct intensity, and
  2. The other wavelengths of light you are exposed at the same time (that may influence the effect of red light on your body - for example, red light can help with collagen production and wrinkles, but UV light can damage collagen and lead to wrinkles).


Also there is a convenience issue - you have to expose the correct body part to the sun? Is the sun out or covered by clouds? And do you have enough time to get the proper dosage?

For more on this question, I found the following Question and Answer over on the RedLightMan.com website:

Q. What is the concensus regarding the use of sunlight for light therapy? Direct sunlight is about 0.1 W/cm2 in full spectrum, with about 1/10 to 1/3 of that in the therapeutic wavelength bands. The typical therapeutic dose of 60 J/cm2 would thus be obtained in 2000-6000 seconds. So sitting next to the window for an hour should do it, right? The glass filters out most of the UV and is transparent to IR.

A. Joe says:Sunlight in the morning or evening is the best, with more of it being red/NIR. Strength of light otherwise depends on location and time of year.
I think you can get about 30mW/cm2 of light intensity of the relevant wavelengths from midday sunlight in the southern USA in summer. Only about half of this will be really at/near the peak wavelengths. An even smaller amount will be the more penetrative near infrared wavelengths.
It’s not the same either way though. The heating of the skin cells from sunlight can lead to photoaging over time. The relative lack of strength of near infrared around 800nm means deeper penetration won’t be possible with sunlight.
On the plus side, sunlight has some other benefits from the UV.

You can see the full transcript and more on this topic in the article 'Red Light Therapy vs Sunlight'.

Another great article at HeelSpurs.com looks at the difference between sunlight and red light. 
I have quoted some of their main points below:

Bright sun at midday in the southern U.S. in summer has as much energy in the red and near-infrared (600-900 nm) as LED arrays (about 29 mW/cm^2 ).  But only about 50% of the light in the 600-900 nm range from the Sun is at the best wavelengths, so it requires mirrors and sunscreen to increase the amount of Sun to equal the best LEDs devices which have all their energy concentrated at the best wavelengths.  If mirrors are not used, treatment time is doubled or tripled to get the same benefit as a good LED device, but then getting hot becomes a problem if you don't have a fan and a mist of water to keep cool.

There are three ways [RLT] might be possible to provide equal or greater benefit than the Sun for hypoxic or injured cells: 

1) LEDs can provide injured cells with a larger amount of light in the beneficial range and at times when the sun is not available,  

2) we can reduce the heat and thereby provide higher concentrations that reach deeper cells (the Sun is limited to about 1/2 to 1 inch of depth like most LED and laser units),  

3) in the future an inexpensive device will be made that is specifically tuned to the cytochrome c oxidase (CCO) set of proteins, having a specific sequence of pulse times of specific wavelengths and pauses, forcing CCO through each step of its pumping action with minimal heat and maximum depth. 


Remember, there are many benefits of sunlight exposure, and red light therapy is not an alternative to getting full spectrum sunlight. Ideally you would get both - beneficial full spectrum light from the sun (helping you wake up in the morning, boosting vitamin D levels, helping mood etc) and also beneficial red light from a red light therapy device.

  • Does red light work as a SAD light?

No. A Seasonal Affective Disorder (SAD) light is intended to help you overcome lack of sunlight. SAD lights should provide full spectrum light - ideally mimicking the light emitted by the sun.

Red light only emits a small portion of the sun's full spectrum light.

For more on SAD lights please read What You Need To Know About Seasonal Affective Disorder (SAD) Lights

  • I see some people using blue lights in their devices, what are the differences between blue and red lights?

Blue light has a completely different effect on the body than red. Blue light has been shown to damage mitochondrial function (Our cells powerplants).

For instance, blue light suppresses melatonin and disrupts sleep, and it can damage our eye health. 

However, there are some studies that show blue light can help with acne - as the light kills the bacteria in the skin linked to acne. This is often why you see blue light panels at health spas and skin clinics.

Due to the damaging properties of blue light and the fact that we live in a world saturated in blue light (whilst lacking in red light) I would personally recommend avoiding blue light devices.






What You Need To Know About Using Red Light Therapy Devices

  • Can I use red light therapy devices more than once a day?

Sure. Just be aware that for optimal results, there is an upper limit to the dose of your red light therapy. After that you may see diminishing returns.

More is not always better. Saying that, the the risks associated with overdosing red light therapy are much lower than say overdosing with UV light.

Using too much red light usually means that the effects of the red light therapy are greatly diminished. Diminished effects mean that you simply won't gain any benefit from the session—UV light on the contrary, can actually damage you when you apply too much of it. 

This optimal dose means that red light therapy follow a reversed U curve, where either too little or too much red light therapy offers no benefits, and only optimal dosing offers the most benefits. 

As you can see in the picture above, it's still important to get the dose right in order to get the most benefits from red light therapy (more on this below).

The dose of red light exposure varies between your goal, distance from the device, the device itself etc and of course the time spent using the device, there is no reason why you can't use your RLT more than once a day. Instead the question should be asked - do I need to use it more than once a day?


  • Do I have to wear eye protecting goggles when using red light therapy devices?

I am asked this question a lot and have done a lot of research into finding the answer.

After speaking to many Red Light Therapy experts - the common answer received is 'no, you don't have to wear eye protection when using red light therapy'.

In fact, there are a lot of studies showing that RLT is in fact beneficial to eye health - particularly red light around the mid 600nm wavelength (14-17). And I could not find any studies showing that red light therapy harmed the eye.

The team from Joovv asked on the of most respected experts in the field of photo-medicine this exact question. The answer:

"No, it’s probably good for your eyes. Light therapy can help with cataracts…Infrared LEDs can preserve your retinal photoreceptors from damage."

For the full answer and more resources to support this answer, please read 'Do I Need To Wear Eyewear' at Joovv.com.

Gembared, a new company selling RLT panels, has this statement on their website in regards to eye protection:

Red light is generally fine to look at, however be aware if you have any light sensitivities specific to you. We recommend initially using the product in a well-lit room to allow your eyes to become accustomed to the light. Keeping your eyes closed or looking away from the light while it is near the face is another good option. Please feel free to use goggles or sunglasses as you see fit or if your doctor recommends it.

You can also look at these three studies showing the benefits of red light for eye health:

Though I should point out, I know some users prefer to wear eye goggles when using their red light device.

[Update] I found a really good analysis of light and eye health that can be read here - Safety Concerns with Infrared Light 

They article shares the same view as the above comments - that red light (600-700nm) is safe for eye health. But of concern is infrared light - as this may cause the eye to overheat.

Some of the referenced papers in the article look at 850nm wavelength. The author make's it known that the levels used in the research are similar to what you would receive on a clear day at the beach or snow. But still there is a possibility of longer term issues with eye health.

My takeaway - if you are using 850nm Near Infrared on your face/eyes, then it may be best to keep your eyes closed while the light is on. This will help lower the amount of NIR light potentially heating the eyeball.

Also, the article mentions a few other points:
- Blue light is 1000x more dangerous to the eye. This is covered in more detail HERE.

- RLT can help with eye wounds


  • How long do I need to use red light therapy to see the benefits?

Like many things related to health - the answer is 'it depends'.

It depends on the device used, how long you use it for, your health problem etc etc.

I personally saw tremendous health benefits in a few weeks of regular use (read more about my experiences here). I know of family members and clients that have noticed less pain and inflammation from using a red light device after 1 session.

And I also know that red light devices speed up wound healing and help me recover from gym workouts - this occurs after only a handful of sessions.

Meanwhile something like hair regrowth using RLT seems to take much longer - months, maybe even years of regular use before you see the benefits.

As mentioned, it depends on many variables. The biggest variable being 'what do you mean by benefits'.

I highly recommend reviewing THIS document that lists all the peer reviewed studies done on red light therapy for various medical conditions. I suggest you find the condition that you are seeking to improve within the document, and look at the studies related to that condition.

Read up on the dosage protocol and of course the time needed to see results. This may be a more scientific way to find an answer to this question.


  • How long should a Red Light Therapy session last? How much light exposure do I need to see benefits?  How long should I use my red light device?

It's very hard for me to give exact guidelines on how long you should use any device, because the specific device, your distance to the device, and the reason for using red light therapy, all need to be taken into account. 

For example, if you are using red light therapy for treating scar tissue, this goal merits the application of a lower dose than when you are using red light therapy for joint pain. The reason for this difference is that joints are located deeper into the body compared to the skin. Not all red light applied to the skin will reach the joints, as some of the red light photons are taken up by other tissues in the process. 

Please consider whether the company that you buy a red light device from offers any dosing guidelines. If such guidelines are not included with the product, then you should check to ensure the device you are buying offers power output measurements.

From there you can devise a dosing protocol specific to your machine and your goals.

The key unit of measurement you want to understand are:

  1. Dose - 'Joules per centimeter squared' or J/cm². This figure will show the amount of energy delivered to an area for a time period.
  2. Power Density - milliwatts per centimeter squared or mW/cm². This figure shows the power output from the light for an area.
  3. Time - seconds

These values can be inputed into the following formula:

Dose (Joules per cm2) = Power Density (mW/cm2) x Time (s)

For example, using a device an intensity of 100mW/cm2 for 60seconds equals 6 Joules.


If the manufacturer cannot provide the power output numbers then I recommend avoiding this device. For more help on buying a red light device, please see my Red Light Buyers Guide HER.

The key value you want to find is the 'dose' (joules per cm2). This figure shows the amount of energy applied to the body. Once you have this, you can then look at what the optimal dosage is for a particular health issue. For instance, the effective dose for wound healing is 90 J/cm² (18).

If you know the dosage figures from your device, then you can simply calculate the time required to receive this dosage. For example, my Joovv panel emits approximately 60 joules within 10 minutes standing 6 inches from the device. So if I was seeking optimal wound healing results with my Joovv, I may aim to spend 15 minutes in front of the device etc.

Note - distance from the light source has a great impact on the light energy hitting the body. Being further away from the light source increases the total area covered but requires a larger amount of application time. Standing closer to the panel decreases surface area coverage but increases energy concentration.

Though for an extremely comprehensive guide to this topic, I recommend reading the article  'Complete Guide to Light Therapy Dosing - by RedLightMan.com'.

In this detailed article, the author covers topics such as 'finding the strength of my light, how to calculate dose requirements, and effective doses needed'.

The list of doses needed for various goals is very useful. 

If you are super serious about getting optimal results from your red light device, then I highly recommend you spend some time reading this article to determine precise dosing guidelines for you and your device.

Also, the team at RedTherapy.co have created an iPhone app to help determine optimal times. The app is called RedRush. The power dosages used in the app are based on the panels sold by their company - which is fair enough.

Though it would be neat if you could input your devices specs and have the app work out all the ideal times etc. Saying this, the RedTherapy.co panels are similar in power output to the Joovv panels. So Joovv owners may be able to use the app for their device.

If you don't want to crunch numbers and try to understand terms such as power density, joules per centimeter squared, and irradiance, then I would suggest you simply follow the guidelines that come with your red light therapy device.

Me personally I don't bother too much with the numbers. On a typical morning, when following my morning routine, I aim to spend anything from 5minutes to 12 minutes in front of my Joovv before rotating and dong the same on the other side of the body. You can see more about this here.  

Also, for more on the importance of dosing, power density, joules and an interesting look at how the skin blocks a large percentage of light (and in turn more powerful devices are recommended) please see the article LED Strength and Dose at Heelspurs.com.

And if you are confused about wattages, power intensities and irradiance when it comes to red light devices, be sure to read this great article - Measuring the Power of Light Therapy Device.

  • Will the red light device impact my sleep?

It is well established that blue light suppresses melatonin, raising cortisol and disrupts sleep (19). A quality red light therapy device should not emit any blue light.

But there is evidence that red light can have a minor impact on slight if the light intensity is strong enough (20).

I have personally used red light in the evening and haven't noticed an impact on my Oura Ring sleep score. But I do have friends and clients that have noticed their sleep suffers when using red light right before bed.

For these reasons, you may want to aim to do your red light session in the morning. Failing that, aim to do your red light session as far away from your bed time as possible.

But all these is irrelevant if you're not blocking blue light in the evenings and wearing your blueblockers!

  • When I use my Red Light Therapy device, everything seems green and blue. Why is this?

The eye is being saturated in red light when exposed to red light devices, in turn the eye increases sensitivity to other colors such as blue and green. 

When you move away from the red light source, it takes a while for this sensitivity to normalising - making your world seem a lot more blue while the red hues are toned down.

It will only take a few seconds to adapt back to baseline.

For more on this topic, the team over at RedLightMan.com had the following to say:

Your eyes will adjust to the bright red light after a few sessions and it will even be beneficial for them, improving general vision and preventing AMD/cataracts/etc. If you are very sensitive, you should use near infrared light on the face, rather than red (since near infrared is invisible and doesn’t overstimulate the eyes). You could use something like THIS for full body treatment having the near infrared panel in front of your face and the red panels on the body.


  • What wavelength light should I get?

It depends. It depends on what you want from your device. There is a plethora of published papers showing the effectiveness of certain red light wavelengths to help the body. I have created a guide that can help you find out what wavelengths are best for a particular problem HERE.

But in the comprehensive meta-anaylsis on light therapy titled The Nuts and Bolts of Low-level Laser (Light) Therapy (21), the researchers stated:

The wavelengths of light used for (light therapy) fall into an “optical window” at red and NIR wavelengths (600–1070 nm). Effective tissue penetration is maximized in this range, as the principal tissue chromophores (hemoglobin and melanin) have high absorption bands at wavelengths shorter than 600 nm.

Wavelengths in the range 600–700 nm are used to treat superficial tissue, and longer wavelengths in the range 780–950 nm, which penetrate further, are used to treat deeper-seated tissues.

Wavelengths in the range 700–770 nm have been found to have limited biochemical activity and are therefore not used.

If you are trying to chose a device with the 'best bang for your buck', you may want to find something that has minimal energy going to 700-770nm light. For example, the Red Light Man half body panelshave power equally split between 620nm, 670nm, 760nm and 830nm wavelengths. Though all ranges are within the 'optical window', the 760nm light may be wasted when it comes to health benefits according to this report.

Whereas the Joovv Half Body combo panel only emits two wavelengths - 660nm and 850nm (Read my review on this Joovv Half Body Unit here). Sure this is less variety, but at least you know that all the light being emitted is well utilised by the body (and both the mid 600 and mid 800nm wavelengths have a lot of evidence behind their effectiveness)

Whats the difference between 660nm and 850nm?

In simple terms, the 660nm light is absorbed faster by the skin, useful for those who want to reduce wrinkles, boost collagen, and reduce scars and stretch marks.

The 850nm light goes deeper into the body, helping with inflammation and joint pain and muscle and organ recovery and health.

  • Can you tell me how to use red light to boost testosterone?

Optimal hormone functioning actually starts in the brain. Different brain areas, such as the hypothalamus and pituitary gland, are involved in that process. Up until recently, however, it was not known that thyroid function also affects steroid hormone production.(23)

Improving thyroid function will thus also improve steroid hormone production, such as testosterone. To accomplish this effect, you specifically need to use the red light device on your thyroid. 

In addition to improving steroid functioning through thyroid hormones, red light therapy can also increase steroid hormones such as testosterone by directly stimulating the energy production in organs associated therewith. An example would be testosterone production in the testicles.(25)

Remember that red light can penetrate deeply into the body, thereby increasing energy production in specific organs. When the correct dose of red light therapy is applied to the testicles, it might actually increase testosterone levels up to threefold.(26)

The guys over at RedLightMan.com have put together a great article on using red light to boost testosterone and fertility. You can see this here - Red Light ‘Triples Testicle Function’ Studies Show.

A few key points from this article are:

  1. In most cases, red light therapy directly on the testicles for short, regular periods would raise testosterone levels over time.
  2. Stick to LED light therapy for maximum safety and benefits. Visible red (600-700nm) LEDs are optimal. Session time from 2-20 minutes depending on light strength/heat.

  3. Red or infrared light from an LED source (600-950nm) can be safely applied to the testes without risk of side effects or damage while delivering all of the benefits as detailed above (improved fertility, improved testosterone production, etc.).
  4. Sunlight can also be used on the testes but only for short periods and it is not without risks.
  5. Avoid exposure to blue/UV.
  6. Avoid any sort of heat lamp/incandescent bulb.

For more ways to naturally improve testosterone be sure to read my article 29 Proven and Effective Ways to Boost Testosterone Naturally

  • Can you tell me how to use red light to help my skin?

 Red light therapy has been proven to improve the looks of the skin, without resulting in any known side-effects.[27] Red light therapy increases blood flow to the skin, thereby increasing the skin's regeneration. 

Additionally, red light activates stem cells around the skin, which then aid them to proliferate into new skin cells. In turn, many skin processes improve, such as reducing acne, inhibiting scar tissue in the skin, reducing sunburn, inhibiting striae, and even aid in healing burning wounds.[28]

Red light therapy can also improve skin conditions such as rosacea, eczema and psoriasis. 

The skin will become tighter and smoother, wrinkles will be reduced in number and decrease in size, and the collagen density of the skin will improve.[29] The feeling of the skin and the complexion of the skin are also enhanced. 

How do you reap these amazing benefits?

Ensure your red light device emits some visible red light (600-700nm range). And aim to use the device for 2-6minutes a day (though duration and distance from the light source are dependant on the power output from the light).

Studies have shown that when using red light therapy for skin benefits, you don't need as high of a dosage requirement as you for deeper tissue benefits.

For more information on red light therapy for skin please see:

  1. Improve the Health of Your Skin with Red and Near Infrared Light Therapy
  2. Collagen Light Therapy by RedLightMan.com
  • Can you tell me how to use red light to help with wound healing post surgery?

The team from RedLightMan.com had this to say about wound healing:

Sure, pretty much all of them are suitable for surgery like that. Red lights will be better for more superficial skin damage from surgery. Near infrared will be better for more substantial deeper tissue damage from surgery. In your case, maybe a combo light would be the most ideal. Using the light at around 50-100mW/cm2 is probably ideal for fairly deeper surgical damage. 5-10 minutes is fine from about 10-20cm away.

  • Can you tell me how to use red light therapy to help with oral health? 

A lot of research has been done on red light therapy and the benefits it has on oral and dental health. Red light therapy applied to the teeth decreases hypersensitivity of the teeth (27,28), reduces harmful mouth bacteria (29), heals wounds and gums in the mouth (30), and increases the bone remodeling after teeth damage.(31)

This means that red light therapy can aid good dental practice, working as a holistic method to improve all-round dental care. 

To use red light therapy for oral care, the light does not only need to penetrate into the cheeks, but light needs to reach the teeth as well. You can simply add a few minutes of red light therapy after brushing your teeth every day. 

If you are using a large red light panel like the Joovv units you would be best to open your mouth when facing the light to ensure you get enough light penetration into the teeth and gums.

I also stand side on with my cheek a few inches from the light to hit the back molars in my mouth. It's important to use a strong red light panel to ensure you get enough light penetration through the cheek.

Me with using my Joovv to heal my gums

This issue is covered by RedLightMan in their oral health article - Red light therapy revolutionary for oral health:

The key requirement for oral light therapy is the ability of the light to penetrate the cheek tissue, and then to also penetrate the gums, enamel and bones. Skin and surface tissue blocks 90-95% of incoming light. Stronger sources of light are therefore necessary with regard to LEDs. Weaker light devices would only have an effect on surface issues; unable to eliminate deeper infections, treat gums, bones and harder to reach molar teeth.

If the light can penetrate the palm of your hand to some extent it will be suitable to penetrate your cheeks. Infrared light penetrates to a slightly greater depth than red light, although the power of the light is always the primary factor in penetration.

We recommend red/infrared LED light from a concentrated source (50 – 200mW/cm² or more power density). Lower power devices can be used, but the effective application time would be exponentially higher.

Red and infrared LEDs are both effective for oral light therapy. Session time from 2-10 minutes depending on light strength/heat. Stronger lights are required for penetration of cheek/gums.

Alternatively, you may want to invest in a smaller hand held unit to help with oral health.

The Infrared Mini 830nm hand held light sold by RedLightMan is one such example.  

  • Does Red Light work through clothes?

If the material blocks light, then it will impact the effectiveness of the red light device. See through clothes or material will allow light through, but thick clothes or black colored clothes will block the light.

For best results, use on bare skin.


  • What distance should I stand from my red light device?

Please see my answer to the question above titled -  How long should a Red Light Therapy session last? - for more on this.

But in a nutshell, it depends.

It depends on the power density of the light. It depends on the dosage you are seeking. It depends on your goal when using the light and your target area.

Also, one thing that should be noted is the potential nnEMF output from the light. Some red light devices have been tested to have very high nnEMF levels (XXX primalhacker?) putting them in dangerous zones.

Others, like the Joovv panels I have tested here - have safe levels of nnEMF output, but there are higher the closer you get to the light source. 

This is why you want to ensure you get a red light device that 1) doesn't have a large nnEMF output and 2) has a strong LED power output so that you don't have to stand right next to the panel.

  • Can I use too much red light? 

Please see the answers to my question on dosing and on side effects above. 

  • What about using red light therapy with animals or plants?

Red Light Therapy has been (and still is) used successfully to help heal animals. Also red light therapy is often used to help plants grow.

For more on this topic, I recommend the following articles:

  1. LED vs HPS grow lights
  2. Grow Lights by RedLightMan.com
  3. Red Light Doubles Vermicompost Production
  4. Red Light Therapy for Animals
  • How effective is red light therapy if used on a wet skin surface? Could I use it whilst in a sauna or a shower?

I couldn't find any research to answer this question. And I don't know enough about the physics of light and water to try and answer it myself. 

So I reached out to the team at Joovv for their answer to this question:

We [Joovv] don't recommend combining light therapy and saunas because the mechanism of action is so different. A sauna is designed to heat up one's core temperature to induce sweat which leads to detox. Light therapy is delivering energy to your body to function at a higher level so mixing the two are actually contradictory to one another, which is why we recommend using light therapy after the sauna to recharge your body after the stress it was just put through. If someone really wanted to place our device in a sauna anyways then, the temperature shouldn’t go past 130F degrees.

[Update] - So I actually found a really neat resource that explains the penetration rate of red and NIR light through water. This is over at HeelSpurs.com.

The graph below was pulled form that article, and it shows light over 900nm starts to get blocked in increasing amounts by the water:

So perhaps a red light could be used in a sauna, or through a shower window, but NIR light would not be recommended.

  • How to get the most out of your red light therapy device?

The team over at RedLightMan.com put together a great piece of information to help you get the most out of your red light device:

How to enhance light therapy’s effects
Light therapy works on the mitochondria in cells to up-regulate energy production and therefore function better, creating better structure. There are a number of other therapies and supplements that help to optimise energy production/structure too:

  1. T3  – Active thyroid hormone (triiodothyronine), improves energy production all over the body. A potent catalyst for mitochondrial respiration. Increases quantity of mitochondria.
  2. Niacinamide – aka Vitamin B3, proven to help acne, anxiety and even yeast infections, niacinamide works by improving ATP mitochondrial energy production. Shows promise for preventing/treating diabetes.
  3. Progesterone topical – Protective steroid hormone, anti-aromatase effect which keeps oestrogen, coritsol, serotonin, etc. in balance. Ultimately helps energy production.
  4. Aspirin – Thought of as regular painkiller, has beneficial effects for health. Similar anti-aromatase effect to progesterone, aspirin also inhibits the COX enzymes which are known to form inflammatory prostagladins from breakdown of polyunsaturated fats.
  5. Methylene blue – Traditionally a dye, more recently discovered to maintain ATP production, especially in the brain. Very safe, even in higher doses.
  6. Dermaroller – Physical device, useful for safe removal of scars. Works by breaking the skin hundreds of times on a microscopic level, which encourages new healing. Especially potent when combined with red light therapy.
  7. Honey – Encourages faster wound healing when applied topically, while also sterilising. Historically used on horses and animals, it works on humans as effectively by providing a matrix and energy for new cells to grow into.

Read more at https://redlightman.com/health/


  • Does Red Light Therapy work through clear plastic or glass? 

 For this question I reached out to Wes at Joovv.com. His response is below:

It really depends on the glass. There are so many different types. To really test this one would need to have an irradiance meter handy to see how well the light is passing through the glass or plastic.







What You Need To Know About Buying Red Light Therapy Devices


  • What you need to look for when buying a red light therapy device

When it comes to buying a red light therapy device you are in luck because there are so many companies selling devices on the market, but the downside is knowing which device is best for you can be difficult.

There are a few things you need to be aware of when buying a red light therapy (RLT) device. Knowing what to look for can help you avoid junk products that may do more harm than could, and can empower you to find the best tool for the job at the best price.

I should preface this answer by saying this - the right device for one person may not be the best device for another. It really does depend on your goal - what you want from the device, and also your budget.

First things first, I recommend you watch this video for a good overview on what to look for (and what to avoid) when shopping for a red light device.

The two most important things to look for when buying a RLT device are:

  1. Wavelength 

  2. Power density / irradiance

Why are these things critical? What do they mean? And what is a good value (or bad)? Read on!


Light is made up of various lengths of waves - blue light has a wavelength of around 450-500nm. Red light is around 600-700nm. Invisible infrared light has lengths above 900nm.

If you are buying a red light therapy device, it's important to know you're getting the right wavelength. Not all red light is equal.

For instance, some wavelengths of red light are better than others. And some wavelengths are better at treating certain conditions than others.

What wavelength should I get?

To determine the best wavelength for you, I recommend reading the question 'What wavelength light should I get?' listed above.

Also, I highly recommend downloading THIS report that shows what wavelength light is best to treat specific conditions.

For those serious about their health, and those who like doing a lot of research to find the best product for their needs, knowing what wavelengths you are after is very important.

Remember - different wavelengths have different effects on the body (and not all wavelengths are beneficial).

Some people may want a device with more invisible infrared light. Others may want more red. Some may want both.

Be wary though - manufacturers may use cheaper LEDS that emit inferior or 'junk' light that doesn't have research to support it's effectiveness, or may actually cause harm on the body (like the high powered blue lights that are often included in skin healing lights).

What is a good - all round - wavelength?

If you don't want to spend hours researching studies on pubmed (or minutes to download my wavelength report here) then I would suggest going for a mid 600nm (630-670nm) wavelength, and a mid 800 (~850nm) near infrared wavelength.

If you find a panel that emits this light (or both of these lights like the Joovv Combo does) then you're on to a winner.

What if the manufacturer doesn't list the wavelength?

Don't buy it. I cover this in my video above. You simply don't know what you're buying.

Unless - you buy it and get your hands on a spectrometer (used to measure wavelength) and test the output yourself? Then if it's emitting junk light, or not the wavelength you were hoping for, return it for a refund.

Otherwise you are taking a gamble - you don't really know what you're buying.

Power density / irradiance

The second thing you need to know when shopping for red light therapy devices is the power density or irradiance. This is a value measured in milliwatts per centimetre squared (or mW/cm2) which is simply the light power over an area. It shows how many photons are passing through an area.

Why it's so important?

If you don't factor in power density, and simply look at wavelength, then you could end up with a low power red light that doesn't have any healing effect on the body.

Even if the light is the exact wavelength you are after, if the power density is low, it's not going to help you reach your goals.

This is why a red LED christmas light is not effective as a red light therapy light source.

It emits red light, but the power density is so low it's not going to have an affect on the body.

Power density numbers are often left out of the sales script for cheap, inferior red light therapy devices. The manufacturers know that their lights are weak, and but they don't want consumers knowing this.

Having adequate power density makes the difference between needing 5 minutes exposure or 50minutes exposure. It's the amount of light that is been emitted.

I explain this concept in much more detail in my question titled 'How long should I use my red light device?' I highly recommend you read through that before investing in a red light therapy device.

What is a good Power Density number?

Again it depends.

What are your goals, how many LEDs are there (100 mid range power density lights in one unit may be better than one high power light), what is your budget...

Generally the higher the power density/ irradiance number, the better the unit (and the less time you need to stand by the unit to reap the benefits).

A few things to note:

Power vs Irradiance 

The power consumption of the unit is different to the power density number. The power consumption is simply the amount of electricity needed to power the device.

It is the power going from the socket to the device before it's been converted to red light. 

Just because a RLT device has a high wattage number, doesn't mean all this electricity is being converted to beneficial red light. This is why high heat output from red light panels means a lot of power is wasted.

Below you can see the difference between power consumption and power irradiance on the Joovv panels. A good manufacturer will share both these numbers, and will not try and mislead the consumer by only sharing the units power figure (in watts)

Power Density at a Distance

Also, power density decreases as you move away from the light source. Make sure you know the power density figure at the distance you will be standing next to the device. For example, some manufactures will list a power density / irradiance figure that may seem good, but they don't state at what distance this figure corresponds to.

If you look at the chart below,RedLightMan.com shows the drop off in power density as you move away from the light source:

You can see the figure of 200mW/cm2 when hard up against the unit, but only a 20mW/cm2 figure when 40cm away. Most people aren't going to press their bodies against the RLT device when using it (and shouldn't anyway, due to the EMF and heat concerns, more on this below).

In reality, you are going to be at least 5-10cm from the light panel when using it. For the example above, this means the actual power density is going to be around 100-150mW/cm2. Not the full 200mW/cm2. 

Another example is by RedTherapy.co. In the image below, you can see how their RedRush 360 panel emits 105mw/cm2 at 6inches, but at 36 inches the power is down to 15mw/cm2.

On the plus side, due to the light angle emitted from the light, the coverage area is much larger.

Be wary of this when shopping for red light devices. If the power density number listed doesn't state the distance it was measured at, assume it's at the light source. Standing next to the light source can be dangerous if the nnEMF levels or heat output is high.

Respectable manufacturers will state not only power density figures, but also the distance measured. Joovv for example, measure their numbers at 6" from the source and publish this on their site. Likewise withRedLightMan

More is Not Always Better

Sure you don't want to purchase a weak RLT device that requires 10 hours of use to get an adequate dose, but you also need to be wary of extremely high powered devices. More is not always better, and saturating the body in high powered intense light may not be beneficial to your body.

Another important thing to note about power density is what you intend on using the light for. If you want to heal deep into the body, or use the light to help heal your gums, you want to ensure the power output is high enough to reach the target area (and penetrate cheeks, skin etc). 

What if the manufacture doesn't reveal the power density number?

Don't buy it until you get these figures. I recommend emailing them and asking what their power density/irradiance figures are for the device. 

And ask them at what distance these numbers apply.

If they don't reveal these figures, you have to assume that the device is junk. Any manufacturer that believes in their product and understands red light therapy will know that power density is an important figure when making and using red light devices.

If they don't share this data, you have to assume they don't want you to know the actual power output, and thus you'd probably be wasting your time and money using the device.

Though that's not to say the device won't be effective, it's just that you won't know exactly what you're working with, and if you want to calculate dosage amounts (as covered in the question 'How long should a Red Light Therapy session last?') then you won't be able to do this.

What about the amount of LEDs in a unit? The team at RedLightMan.com had this to say:

The amount of LEDs is irrelevant because there are different classes/power of LEDs.
The factor that matters is the power density / irradiance (mW/cm2). You need higher than 100mW/cm2 for deeper penetration in general. You want less than 100, but more than 20mW/cm2 for skin treatment.
So what that means is you need to adjust the distance you use something like our Combo light depending on if you want deeper penetration or not.
So you would use it closer than 20cm for deeper penetration. Between 20cm and 50cm for skin treatment.

In summary, when shopping for a red light device, make sure you know the wavelength emitted from the device, and the power density at a certain distance.

Note: For more on wattages, power intensities and irradiance when it comes to red light devices, be sure to read this great article - Measuring the Power of Light Therapy Device.

Personally, I would not buy something without knowing these two values.

But these aren't the only things to keep in mind when looking for a device. You should also factor in:

  1. nnEMF output
  2. Treatment area
  3. Cost


Electronic devices emit non-native electromagnetic fields (nnEMF). These fields can disrupt the body in negative ways. As you are going to be using the red light devices in close proximity to your body, for an extended period of time, on perhaps a daily basis - I recommend choosing a device that has a safe nnEMF reading.

Not all manufacturers publish this data (maybe they aren't aware of it as an issue, or they know their device has bad nnEMF readings so will withhold this data), so if you can't find the answer from them, I recommend searching youtube for some independent tests. I have tested the EMF figures on all the Joovv panels, you can see this here.

Be warned - some red light panels do have high outputs of nnEMF - if you plan on standing or sitting next to these for 10-20minutes or more a day, you may want to look for a device that has a lower EMF value.

On that note, this is another reason why a quality device with a higher power density number is going to be better for your health. If a unit has a lower power density number, it means you have to stand/sit close to the device - the closer you are to the device, the higher the nnEMF output.

Treatment area

The bigger the device, the larger the treatment area. The larger the treatment area, the less time you have to spend using the device (assuming you are trying to reach as much of your body as possible).

The LED's used in a Red Light Device typically angle outwards - sending light off at angles from the LED source. This means that a 10cm by 10cm red light panel may have a treatment area bigger than the size of the panel (i.e. it may in fact be 15cm by 15cm). This may also be referred to as 'lens angle'.

It's important to find out the treatment area of a panel/light before buying. If you want something that is going to cover your back, you may find it only covers 1/3 of the width of your back, in which case you would need to use it 3 times to cover each third. 

Please note however, that if a device has a high lens angle, it will mean that the light fans out from the source, the further away from the device you are, the wider the fan, and the lower the light exposure on the body.

RedLightMan.com have this to say about LED angles:

The angle that light comes out of a light source is one of the main factors in determining how the power density changes by distance. Wide beam angles, such as over 60 degrees, make the power density weaken very soon. Narrow beam angles like 30 degrees keep the power density strong over long distances.

And you may find another device that covers your entire back, so this saves you time (though the price may be higher). Remember though - factor in power density when looking at treatment area.


An obvious thing to factor in when shopping for a red light device is cost.

You may find the best device on the market, low EMF, the perfect wavelengths, awesome power density, good treatment areas, but then the price may be $100k or more (look at the NovoThor for an example of the perfect, but high cost, unit).

NovoThor - it may tick a lot of boxes, but then you see the price tag!


Buy what you can afford, but I highly recommend getting the biggest unit you can afford. Initially you may only want a red light device to treat an injury, but then later on you may want it to treat your skin or heal a larger part of your body.

I originally had the Joovv Original, and was spending 20-40minutes a morning so ensure I got full body coverage. I knew if I had got the Joovv Max I would have been able to treat my whole body in half the time.


Finally there is size. Some devices like the RedLightMans mini are handheld and could be packed in your gym bag or suitcase when travelling (I travel with mine).

Whereas a unit like the Joovv Max may treat the entire body in 10-15minutes, but it weighs 45lbs and stands over a metre tall! So be sure to factor in physical size when shopping for your device.


  • What is the best red light therapy device to buy?

It depends.

It depends on what you want from your device and your budget.

I must say, as an all rounder, I do like the Joovv original combo. Though I am bias as I own the Joovv device and I am affiliated with them (Shameless plug - Use code ALEX to save if you order a Joovv, but note I get a cut as well).

That aside, here's why I like the Joovv Original Combo:

  1. It uses quality LEDS with high power irradiance (100mW/cm2 at 6" from the light)
  2. It is well built - with a solid metal case
  3. It has helped me with a lot of issues (read more HERE)
  4. It has safe levels of nnEMF (I tested them HERE)
  5. The company are transparent and happy to share their specifications and help you get the most from the light.
  6. It covers a big chunk of the body - meaning one 10minute front on session will suffice for an overall RLT dose if you are short on time
  7. The combo uses 660nm and 850nm light - probably the two best wavelengths to utilise (the $100,000 Novothor red light bed also uses these wavelengths).

They also have a larger device called the Joovv Maxx, and a smaller device called the Mini. Both are available with the 660nm and 850nm setup.

The Joovv Original does have a price tag of $1000, and it is a big unit, so it may not be the best device for all.

If you're looking for something smaller and at a lower cost, I like the RedLight Man Mini devices. These have great specs and come in at a good size and price. 

But be sure to shop around. There are a lot of new companies entering the RLT space. 

Some of the more popular ones include:

  • Joovv - one of the most popular RLT therapy companies. Selling high powered, high quality body panels. American based, but ship worldwide.
  • Red Light Man - UK based company selling a wide range of RLT devices, from handheld devices to full body panels.
  • Mitogen - Based in Australia. At the time of writing they are only selling the full bed setup but I am told 'consumer body panels are only weeks away.
  • Gembared - A new company selling low cost, lower powered panels in the US.
  • Redjuvenator - a US company selling mid size red light panels
  • LED Finland -A small Finnish based company selling high quality grow lights and red lights for humans.

Just make sure you read through my Buyers guide so you're not wasting money (or time if you end up with a dodgy device).


  • Why can't I simply use a halogen or incandescent bulb as my red light device?

Traditional light bulbs, such as incandescent or halogen bulbs do emit red light, however,they also emit high amounts of heat with a wide band of wavelengths, and are less effective for very specific therapeutic effects than their LED counterparts. 

Remember, it's not just the light colour (wavelength) that matters, it's also the amount of that light (power density). Read through the answer to the question 'What you need to look for when buying a red light therapy device' for more on this.

  • What is the difference between red light devices and heat lamps like those used by Sauna Space that emit near infrared light (NIR)?

Sauna Space sells heat lamps to enable you to build a home sauna at a low cost. These lamps, like many heat lamps on the market, also impact near-infrared light (NIR). Light that we know is therapeutic to the body in the correct dosage.

But heat lamps are built to put out heat, red light (and even the NIR light) are by products, and are at such levels that the impact of this light on the body is rather low.

Joovv cover this topic in great detail in the article Joovv Versus Sauna Space. I highly recommend giving this article a read, there are also some neat graphics embedded in the article.

Here are a few key paragraphs from the article:

IR heat lamps, like the ones in a Sauna Space, deliver a wide range of wavelengths. However, as you can see in the chart below(click here to see), an incredibly small percentage of the light is actually able to activate CCO. In fact, only about 3% of the wavelengths fall in the mid-600 nm and mid-800 nm ranges. 

Specific to irradiance, there is no doubt IR heat lamps run hot and are definitely not safe to touch. That’s why Sauna Space (and any other distributor of heat lamps) recommends anywhere from 18-24 inches of clearance between your body and the bulb.  However, irradiance is a function of the distance from the light source. And at 20 cm (about 8 inches) from an IR heat lamp, the irradiance drops down to around 10-30 mW/cm2 depending on your position relative to the center of the bulb. But at 18-24 inches away, as you can see in the image below, the actual irradiance falls off significantly:  

  • 7.99 mW/cm2 at 12 inches
  • 4.30 mW/cm2 at 18 inches
  • 2.60 mW/cm2 at 24 inches

To top it off, remember that only about 3% of the energy is even effective for the activation of cytochrome c oxidase. So, as you can see, IR heat lamps are terribly inefficient for RLT therapy.

In summary, IR heat lamps deliver a broad range of wavelengths, with the majority outside of the optical window. And because the irradiance is extremely poor at the recommended treatment distance, they are a poor source of light for the purposes of photobiomodulation (light therapy). Instead, a high-quality PBM device will deliver clinically-proven wavelengths with medical-grade irradiance over a broad treatment area. If you’d like to get into the weeds, here’s an in-depth comparison of how our devices compare to other light therapy products.

In another article I recommend reading titled 'Infrared Heat Lamps vs. LED Photobiomodulation (Light Therapy) Devices' they conclude:

So, while infrared heat lamps create a fair amount of radiant heat across a wide range of wavelengths, for the purposes of light therapy, they are essentially useless.  For that reason, LEDs or lasers are used in virtually all published clinical research in the field of photobiomodulation (RLT).  Increasingly, over the past decade, LEDs have become a popular option because of their low cost and ability to treat larger surface areas.  So, in your search for the best light therapy device, make certain the product delivers the right wavelengths with medical-grade intensity that aligns with the hundreds of clinical studies that have been published over the last few decades.

  • Do I need near infrared red light if I have a full spectrum infrared sauna?

 This is a question I am asked a lot. Before I answer, let me say this - I have a dedicated red light therapy device AND a dedicated full spectrum sauna.

They both have their main purpose. The Joovv Red Light device I use for red light therapy. The Infrared sauna - I use for the benefits of sauna therapy. 

So yes, if you are seeking the benefits from 850nm near infrared light, you should get a red light device that emits such light, even if you have a full spectrum sauna. 

For a really great overview between infrared saunas and red light therapy (included near infrared light) I recommend watching this:

And read this article for more info: Saunas vs Light Therapy (Photobiomodulation) – Key Differences and Practical Comparisons

  • How can I measure the effectiveness of a red light therapy device?

Use an irradiance meter to measure light intensity with an irradiance meter. And wavelength with a spectrometer.

You can also use a solar power meter to measure watts per cm2. But please note these are only suitable when you are measuring a light with a single wavelength source. Lights that emit a range of wavelengths such as standard light bulbs cannot be tested with a solar power meter as there are too many irrelevant wavelengths being measured. 

Though if you are super serious and want a highly accurate wavelength reading, you should get a dedicated infrared light meter to measure light above the 750nm as most spectrometers are designed to measure visible light. The NIR readings may be slightly inaccurate, but this should not matter unless you are doing serious research.

You could also look at using a pyranometer, which measures light energy (in watts) over an area. But it's my understanding that this device won't show the breakdown between power intensity at various wavelengths.


  • What's the difference between illuminance and power density? And can a lux meter be used to measure power density?

Illuminance measures the amount of light (that humans perceive) hitting a surface. The light is measured in lux, or lumens per square metre.

A lux meter measures illuminance, the light intensity of light that is visible to the human eye. With green and yellow being some of the brightest colors in the visible light spectrum.

What about Lux vs powder density? Wikipedia has this to say:

The lux is one lumen per square metre (lm/m2), and the corresponding radiometric unit, which measures irradiance, is the watt per square metre (W/m2). There is no single conversion factor between lx and W/m2; there is a different conversion factor for every wavelength, and it is not possible to make a conversion unless one knows the spectral composition of the light.


This is why a lux meter is not a reliable tool to measure wavelength specific power density (though it is possible to do so, it just requires knowing a lot of technical info around the light source and some math).

You may have also heard of a PAR meter - this is used by plant growers, and it measures the light used by plants in photosynthesis. It is why a Lux meter and a PAR meter will give different results from the same light source.


  • What device do I personally use?

At the time of writing, I use the Joovv Max and a Joovv Original (both with 660 and 850nm light) plus a handheld device similar to the Red Light Man's mini.

I use these every morning, I have the Joovv panels setup in a corner in my office. I stand naked, front on to the Joovv max, with the Original on the side. I then use the mini handheld device to target the top of my head for hair regrowth.

After 5-10minutes (depending on the day), I turn around and have the max behind me and the original on the other side of my body.

Full body coverage in 10-20minutes a day!


  • What is the difference between an infrared sauna and a red light therapy device?

Please see my answer to 'Do I need near infrared red light if I have a full spectrum infrared sauna?' above.

  • Is there a difference between red light devices that flicker or pulse, and ones that don't?

I reached out to the team at Joovv for an answer to this question. Their response below:

There have been some studies with pulsed light that show benefits but I've also seen several that suggest pulsed treatments are no more effective than the sum of the "on" time. So for that reason, our lights use a steady flow of light.There are hundreds of studies proving that this is effective.

For an in-depth look at pulsing and RLT please read Pulsing LEDs for Great Improvement? In this post the author explains how pulsing may be beneficial:

There are four ways pulsing may help:

  1. Strong pulsing will reach deeper tissue. By flooding CCO absorption sites in shallower tissue with short strong pulses, more of the remaining light energy will be available to deeper tissue. Not pulsing at just as strong an intensity will be better because it will require a lot less treatment time, but the device may get too hot.
  2. If there is a "light power threshold effect" in cells, strong pulses may be better.  By this I mean there could be something in tissue that requires a certain amount of "activation energy" to cause a reaction to occur rather than the individual photon theory that I currently have.
  3. If there is something interesting in tissue that responds to certain types of pulsing as described above.  It would take an enormous amount of clever research to determining what kind of pulsing is best (duration, waveform shape, and/or pauses).


  • What is the difference between these red light devices and grow lights that gardeners use?

Power density / irradiance. That is the key difference (please read What you need to look for when buying a red light therapy device above for more on this topic)

The power density on most grow lights is very poor. Typically less than 10 mW/cm2 a few inches from the light. Much lower than the 100-200mW/cm2 ranges that devices like Joovv and RedLightMan emit. 

Speaking of RedLightMan, this is a comment they made about grow lights:

The wide positioning of the LEDs, wide beam angle and so on that you find in these type of ‘grow light’ devices in general make them inappropriate for light therapy.

Like many things in life, you get what you pay for. A $30 red LED grow light on amazon is not going to have the same power properties as a $1000 specifically designed red light device.

Grow lights are designed to help grow plants. Red Light Therapy devices are designed for red light therapy.

  • My local salon/gym/health centre has a red light, is this a good device?

It depends on the device they are using.

If it's a NovoThor or a MitoGen red light bed, then yes, it's a great device! Probably the best on the market (these units can cost over $100k!)

Otherwise you may need to do some digging around the quality of the device. There are many companies selling red light therapy devices, some good and some bad. I would suggest you find out the name of the device they have at your centre, and then look on the companies website for the technical specs.

Cross check this info with my red light buyers guide report to see if it's up to standard.

RedLightMan.com had this to say about this subject:

I wouldn’t expect your average salon to know much about wavelength or power density. There’s quite a steep learning curve on the technical aspects of light therapy. I’m not sure about the red bulbs used in those tanning beds. They don’t seem to be studied at all by researchers. It makes sense for now to stick with LEDs or low level lasers.


That's a wrap!

If you read through all of this and still have a question about red light therapy, please post it below and I'll do my best to cover it.

Also - if you have any links, resources, studies or thoughts that readers and myself would appreciate to hear, please leave them below.

Finally, if you are looking at buying a red light device, make sure you download my FREE buyers guide by clicking HERE.


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