Red Light and Infrared Light Therapy

Alexis Wilson
9 min readJul 2, 2020


Red light therapy, also known as photobiomodulation, has increasingly gained traction over the last few years. It is used for everything from scarring and wrinkles to testosterone increase.

To make things easier I will classify both red light therapy and near-infrared light (NIR) as red light therapy throughout this article.

As the number of “biohackers” and people who want to maximise their health increases. I admit, I fall within that category, as someone who loves to optimise my lifestyle. In this article we will dive into the science behind red-light therapy, how to use it and everything you need to know to maximise benefits.

What is Red Light Therapy

Red light therapy is the use of certain light wavelengths to improve multiple aspects of health. It started becoming known after NASA did research into the use of different wavelengths to help plants grow in space. Research found that red light at specific wavelengths and intensities promoted plant growth.

Following this success, researchers looked into the use for human beings, as a way to treat multiple issues astronauts experience while in space, such as slow wound healing.

You may have heard of red light therapy by other names such as:

  • photobiomodulation (PBM)
  • low level light therapy (LLLT)
  • soft laser therapy
  • cold laser therapy
  • biostimulation
  • photonic stimulation
  • low-power laser therapy (LPLT)

The thing to bear in mind is that there are only specific wavelengths which have been found to be beneficial. On a day to day basis you will see large spectrum of light outside.

The devices, which are totally harmless, are technically just normal lights. If they are of a therapy grade however, they are quite powerful and have a profound impact. For the lights to work they need to use particular wavelengths.

The 2 most commonly used wavelength are around 660 nm and 820 nm. 660 nm is known as red light therapy, as this is within the visible spectrum of light. Think of a strong red colour, much like the bright red that has given red light districts their name, whereas 820 nm is known as near-infrared light . This wavelength is not visible to the naked eye. The light which include this wavelength look as if they haven’t been turned on bit very much have an impact on the body.

The Benefits of Red Light Therapy

Let’s dig into the science or what is can be used for. What’s great about this tool, is that it has been researched since the 1990s. This means, that we know exactly what it can be used for, at what intensity and more.

Mitochondrial Health

The mitochondria are usually described as the little powerhouses of the cells. In other words, they are responsible for energy production and if they stopped we would die within seconds. The process during which mitochondria make energy (ATP) is known as cellular respiration.

Science Bit (you can skip this section)

There is a growing amount of evidence that red-light and near-infrared light affects cells via a photoacceptor known as cytochrome C oxidase. Because cytochrome C oxidase is a the terminal enzyme in the electron transport chain a negative impact on it will reduce ATP production. It was recently discovered that red light at a 670 nm can modulate the effect of certain molecules that inhibit cytochrome C oxidase.

Skin Health and Superficial Anti-Aging

A study looking at red light therapy showed the following results after 30 sessions (twice a week). It displayed the increased the increase in collagen within a 46 year old females skin using red light therapy. As is clearly visible, the collagen density increased significantly. This is great news for us!

This is one of the reasons people use red light therapy the most — skin health and anti-ageing. Most likely, this is where you heard about red light therapy the first time. You’re in luck, the science is on your side.

Studies have found that red light therapy in the ranges of 633 nm and 830 nm reduced the visiblity of wrinkles in the face of the subjects over a 12 week. Intially, it was discovered that in animal wound models, there is an increase in collagen production and as a result improved healing.

Randomised, placebo-controlled and double blind trials also found a reduction in wrinkles with the exposure of red light therapy twice a week. The results found that there was a 36% reduction in wrinkles and an increase of skin elasticity by up to 19% compared to the baseline. It resulted in an increase in collagen and elastin fibres. The scientists concluded that 830 and 633nm LED phototherapy was an effective approach for skin rejuvenation.

The image above, from the same study as the collagen images, displayed a very clear reduction in wrinkle depth and visibility.

Recovery and Performance

Recovery and performance is another reason some people reach to red light therapy, especially athletes. Although this is more a niche, I’m sure the amount of people who use this tool will increase over time as the knowledge spreads. A study comparing 3 groups to look at muscle recovery and muscle gain found that the group exposed to red light therapy had a greater increase in muscle thickness and increased force (torque).

Cold Sores and Mouth Ulcers

Red light therapy appears to help with the reoccurance of cold sores. Cold sores, which are caused by the herpes simplex virus, break out when the person’s immune system is not functioning 100%. For example, after sub-optimal sleep or when suffering from a cold. A study from Vienna found a significant reduction in cold sore recurrence, with the authors concluding;

In conclusion, we demonstrated that a total of 10 irradiations with low-intensity laser therapy significantly lowers the incidence of local recurrence of herpes simplex infection

Inflammation and Pain

Red light therapy has been researched as a therapy for different ailments, including rheumatoid arthritis. This study showed particular benefits, including a reduction in morning stiffness and a reduction of pain by 70% compared with a placebo.

Cognitive Function

Cognitive function has also been shown to increase with the exposure to certain wavelengths. A few studies have looked at the effect on dementia and other neurodegenerative diseases and found promising results. The studies shown below all used NIR light therapy.

Additional studies have a looked at improved cognitive function in participants exposed to transcranial (onto the skull) red light therapy. Again, these studies showed promising results, with patients making fewer mistakes.

Wounds and Burns

A lot of research has been undertaken to examine the effect on wounds and wound healing. This was some of the original research conducted for use by NASA. Since then, more research has been conducted to investigate diabetic wound healing. It was found that wounds heal significantly faster when exposed to red light therapy.

Researcher’s found that collagen production increases with exposure to red light, resulting in accelerated healing.

Hormonal Health

Men are obsessed with testosterone, as it is associated with being manly. The great thing is, there have been quite a few studies investigating whether hormone levels and sex drive can be optimised with red light therapy. Interestingly, those in the northern hemisphere experience in a drop in testosterone in the winter months (Nov-April). Scientists theorise that this is due to a reduction in light exposure. Levels begin to rise again in the summer months, which lends a little credence to theory.

A pilot study in in males over 40 with low sexual desire found an increase in testosterone levels in a placebo controlled trial. With this increase came an increase in sexual satisfaction. In this study a light box was used.

In a rat study, scientists observed a significant increase in testosterone when the testes of the rats were exposed to 670 nm wavelength light therapy. It should be noted that longer wavelengths such as 810+ nm way not yield beneficial effects (at least on rats). The scientists concluded the following:

Our results showed that the LLLT using a 670-nm diode
laser was effective in increasing serum T level without
causing any visible histopathological side effects to the
tissue. Thus the low level laser therapy may be an alternative treatment modality for conventional types of
testosterone replacement therapy.

An additional study, drew conclusions by analysing the results form multiple human and animal studies. The authors concluded that red light therapy should be used as it is safe and effective for increasing fertility in animals as well as animals. The authors suggested using a mix of wavelengths. Pulsed as well as continuous exposure was recommended. 635 nm appeared to be the number that cropped up for pulsed as well as continuous exposure. This ties into the previous study.

Finding the Right Light

In this section we will be referring back to Dr Hamblin every now and again. A greatly respected researcher and fountain of knowledge when it comes to red light therapy.

Light Flicker

Flicker is something that is worth considering if you’re looking at purchasing or using very cheap devices from relatively unknown brands. If one purchases cheap LED lights from local hardware stores then flickering might be an issue. Essentially what happens is that the current changes direction and as this happens the lights turn on and off.

You may remember what it looked like when you tried to film a computer screen and you saw lines travelling across the screen. This is because of the light turning on and off rapidly.

The problem with flickering, is that it’s so quick, we cannot pick it up consciously. Long term, it can lead to eye-strain and fatigue. Such as many people experience with prolonged computer use.

Generally speaking flickering is not a concern if the LED lights used are of a high quality and the power output is sufficient. Most reputable brands don’t have significant issues with flickering. Many brands are also evaluated by 3rd parties to make sure that the quality mentioned on their respective websites is accurate.

It has been mentioned that pulsing or flickering may actually be beneficial when using red light therapy. During long term exposure work however it isn’t beneficial and does cause eye strain.


The intensity is a crucial element of red light therapy. Too little and it won’t have an impact, too much and it may be counter productive. The truth is, that more isn’t always better. To the point that some studies use short 5 minute exposure multiple times a day (at a lowish intensity) rather than blasting the subjects with high intensity for long durations.

So let’s dive into the nitty gritty details. Dr Hamblin,A harvard based researcher on the subjects, suggests that the cap is around 100 mW/cm2. Below this range is where one gains the most benefits.

The graph is from a study which examines the dosages at which red light therapy begins to have a significant impact and when it the intensity is too high. This graph is an idealised version from earlier studies but it is a great visual to gain an understanding of the concept. More is not always better.

EMF (Electro Magnetic Frequency)

EMF is currently hotly debated, with many scientists agreeing that it has an impact on the body. Many disagree on whether the effects are negative however. Personally, I like to err on the side of caution. If you want to know more about this topic I suggest you read the book “The Non-TinFoil Guide to EMF”.

All devices release some kind of radiation, be it magnetic, electronic or microwave. Many companies focus on keeping the EMF as low as possible.

There are devices that can be purchased to measure the EMF output of devices and electrical wiring. Having spoken to other people , as well as read measurements taken by other people, it appears that most devices aren’t a great concern. As perviously mentioned, all the leading companies know that this is something potential buyers look at and as result do their best to reduce. In addition, your exposure will also be fairly short. After all, you aren’t carrying in it your pocket all day like your mobile phone.

Blue Light

If you’re looking at buying a cheap device or worse, just purchasing some LEDs, you may not get a the right wavelengths. In addition, there could be some blue wavelengths. As you may already be aware, this is suboptimal for the results you are looking for. In addition blue wavelengths are a no-go in the evening, as they tell the body it is daytime resulting in poor sleep quality.

This is one of the reasons blue light blocking glasses are becoming eve more popular and should be part of everyone’s evening routine.



Alexis Wilson

I have an avid interest in all things human body and health. Owner of Reignite