What Does Red Light Do To The Brain?

Author : Ari Whitten
Medical Reviewer: Evan Hirsch, M.D.

RLT and the Brain

Red light therapy has been proven to be effective in treating a number of skin conditions, inflammation, sleep disorders, and even anti-aging. As a safe and minimally invasive solution, infrared light offers an effective alternative to traditional drugs as a method of healing wounds and promoting cellular energy. LLLT is FDA-approved for treating conditions like chronic joint pain, hair loss, and may even help regenerate brain tissue. 

But how does it work on the brain? In order to discuss this topic thoroughly, we will start by taking a look at how it all started….

The Beginnings of Red Light Therapy

In the early 1990s, NASA began studying red light spectrums in order to determine the beneficial effects on growing food in space.1 

Researchers around the world took note, and increasing amounts of research have been devoted to the effects of RLT on bio-organisms. Specifically, the wavelengths of light between 660nm (red) and 890nm (infrared) were found to be “bioactive,” meaning having an effect on living tissue.

The basic process of RLT and near-infrared (NIR) infrared therapy involves exposing cellular material to red and NIR light by means of low light lasers or LED lights. The process is known by many names, including:

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

I go into more detail on how RLT works in this recent blog post. How Does Red Light Therapy Work?

How Red Light Affects Bio Organisms

The premise of red light therapy is that the wavelengths of light cause a biochemical effect in cells that boost the energy production of mitochondria. A cell’s energy is created in the mitochondria as adenosine triphosphate (ATP).

You can think of the mitochondria as the powerhouse of the cell. By increasing ATP production, the cell has more energy to function more efficiently and repair damage.

Red light therapy doesn’t cause damage to the skin’s surface, which differs from laser or intense pulsed light (IPL) therapy. Light wavelengths work by causing damage to the outer layer of skin, inducing tissue repair. Differently, red light penetrates only about 5 millimeters into the skin, directly stimulating cell regeneration and collagen production.

LED light therapy is also thought to contribute to hormesis, building up the cell’s anti-oxidant and anti-inflammatory defense systems.

Red Light Therapy and Brain Health

Red light and NIR light, when applied directly to the head, preserve and regenerate brain cells and tissue. A high-quality device is able to penetrate the skull and produce more metabolic energy by stimulating the mitochondria. Other benefits of stimulating mitochondrial functioning include increased cerebral blood flow and increasing the availability and consumption of oxygen. 

The specific mechanisms of the effects of red light are the increase of cytochrome c oxidase activity, activation of cell signaling pathways, up-regulation of transcription factors, and increasing the expression of protective genes.2

Dr. Michael Hamblin, Associate Professor at Harvard Medical School, notes, “Near-infrared light can penetrate quite deep into the body. So if you shine it on your head, it will penetrate your skull and a lot of it is absorbed by your brain. Once you understand this, it’s amazing to think of the various diseases of the brain that need regeneration and healing, which could potentially be treated with infrared light therapy.”3

RLT for the Brain

Improvements for Memory, Attention, and Reaction Times

A study published by Barrett DW, et al in 2013 examined the effects of infrared on the brain in one of the first placebo-controlled human trials. The results for cognitive function were very positive and impressive:4

  • Quicker Reaction Times: “Significantly improved in the treated vs. placebo control groups” in sustained-attention psychomotor vigilance task (PVT).
  • Better Memory: “Showed significant improvement in treated vs. control groups as measured by memory retrieval latency and number of correct trials” in delayed match-to-sample tasks.
  • More Positive Moods: “Overall affect improved significantly in the treated group due to more sustained positive emotional states.”

Red Light Therapy and Stronger Learning

A 2017 study tested 118 people who received infrared light or a placebo. Then participants had to learn a series of categories and rules to test their ability to integrate knowledge and conditions. The study concluded that rule-based learning was greatly increased in the subjects who received RLT compared to the control group.

“We found that prefrontal rule-based learning was substantially improved following transcranial infrared laser stimulation as compared to placebo. These results highlight the exciting potential of transcranial infrared laser stimulation for cognitive enhancement and provide insight into the neurobiological underpinnings of category learning.”

Red Light Therapy for Better Reaction Time

In another recent study, 31 participants between the ages of 14 and 65 were tested on event-related responses before and after RLT.5

The medical research concluded, “The data suggest that NIR light may have an acute effect on reaction time and amplitude in certain subject subsets. There were no adverse events registered across the 31 subjects in the treatment group, nor in the 18 evaluable control group subjects.”

Red Light Therapy and Age-Related Cognitive Decline

Researchers examining neurocognitive function in adults age 49-90 who complained of memory loss. Specifically, the study looked at prefrontal cortex measures, including attention and short-term memory. 6

  • The authors noted that “all participants improved in all cognitive measures after light treatments”.
  • Cognitive improvements included significantly quicker reaction time, fewer lapses, and more correct responses in tests.
  • “Importantly, no adverse effects were found.”

An additional study published in the International Journal of Geriatric Psychology found similar results when studying RLT and age-related cognitive decline. Researchers tested frontal brain activity in older adults after participants received light exposure or a placebo. 7

Researchers concluded, “Only the older adults who received real treatments exhibited significant improvements in their action selection, inhibition ability, and mental flexibility after vs before treatment.” 

Traumatic Brain Injuries

Red light therapy is being examined for the treatment of traumatic brain injuries (TBI) and chronic traumatic encephalopathies (CTE), such as those received in military harm or contact sports. 

Studies and trials have been promising and show that light exposure may increase the growth of synapses and new nerve tissue in damaged brain cells and help improve cognitive performance.

One study concluded, “Many investigators believe that PBM for brain disorders will become one of the most important medical applications of RLT in the coming years and decades… If inexpensive LED helmets can be developed and successfully marketed as home use devices, then we are potentially in a position to benefit large numbers of patients (to say nothing of healthy individuals).”8

Dr. Hamblin and I go over the Science on Red Light Therapy Benefits in this podcast.

Researchers at the VA Boston Healthcare system are testing the effects of light exposure on brain function in veterans with Gulf War Illness. “We are applying a technology that’s been around for a while,” says lead investigator Dr. Margaret Naeser, research linguist and speech pathologist, “but it’s always been used on the body, for wound healing and to treat muscle aches and pains, and joint problems. We’re starting to use it on the brain.” 9

Naeser sees potential not only for war injuries, but also for such conditions as depression, stroke, dementia, and even autism. “There are going to be many applications, I think. We’re just in the beginning stages right now.”

Alzheimer’s Disease and Dementia

Trial results are encouraging for the treatment of Alzheimer’s Disease (AD) with red light therapy.

A 2017 study examined the effects of NIR stimulation using 1060-1080nm light emitting diodes. The study concluded, “Results showed changes in executive functioning; clock drawing, immediate recall, praxis memory, visual attention and task switching (Trails A&B) as well as a trend of improved EEG amplitude and connectivity measures. Neuroplasticity has also been reported with NIR light stimulation and mitochondrial enhancement.” 10

It is showing promise for improving brain health, including memory and cognition, as well as treating brain diseases and injuries. If you are interested in investigating RLT, it is always best to consult with your healthcare professional to discuss the best RLT options. 

Now that you understand how red light therapy works with the brain, you can get even more information on the science behind its effectiveness, health benefits, tips to get the best results, and MORE by clicking here.


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Medically Reviewed ByEvan Hirsch, M.D.

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