How Red Light Therapy Works For Sleep？

Red light therapy works because the light doesn't just hit your skin but penetrates into your body. That way, the red and near infrared affect you at the cellular level. Red light therapy can lower inflammation across the body, for instance, while increasing energy production.

And, that increase in energy production results in many processes in the human body running much more smoothly. You can think about energy as the universal currency within biological systems - the more energy you have, the better you perform and feel.

Besides energy, many other processes are influenced by light as well. Examples here are the circadian rhythm - the circa 24-hour day and night cycle in your body. And, all of these processes that are affected up to the cellular level also influence sleep.

Study 1: Better Mood, Less Drowsiness, More Quality Of Life

A 2022 study used infrared light only to improve sleep quality (1). That near-infrared light was emitted at the 850nm wavelength. In total, 56 participants were included in the study. All participants had mild sleep complaints. Exposure to the near-infrared occurred five times per week for four weeks. The light therapy was applied in the morning time.

Also, the light therapy was used in both the summer and winter time to deal with seasonal variation. That turned out to be a great choice from the researchers, as decent results were found when red light therapy was applied in the winter but not in the summer.

Study 2: Less Sleep Requirement (Implying Faster Recovery) And More Deep Sleep

Study 3: Red Light Therapy Improves Sleep Quality And Cognitive Performance For People With Cognitive Decline

I can't find a full text of this 2022 study so I can't do a full analysis of the outcome here (5). Suffice it to say that red light therapy was applied to the prefrontal cortex, which is the brain area above your eyes, in patients with subjective cognitive decline.

The study participants were split into a placebo and treatment group. After five days, the treatment group saw increases in the amount of deep and REM sleep they received, while the percentage of light sleep declined.

The participants receiving the light therapy treatment also performed better at a brain test that uses working memory and processing speed called "dual n-back". The prefrontal cortex plays a major role in the performance on that test.

Study 4: Female Basketball Players Improve Melatonin Levels, Endurance, And Sleep Quality With Red Light

Next up, a study with 20 athletes of the People's Liberation Army (6; 7). The athletes were 18 years old on average and play basketball. Ten of the athletes received red light therapy and ten a placebo. Sleep quality was measured with the Pittsburgh Sleep Quality Index (PSQI). The PSQI is a widely used valid and reliable sleep measurement tool, although imperfect (8; 9; 10).

The athletes also had their melatonin levels measured and did a 12-minute run test. In the intervention group, red light therapy was applied daily for two weeks straight. The red light therapy lasted 30 minutes and was applied with a bed. The wavelength used was 660nm. A 30 J/cm2 dose was applied, which is great for deeper tissue treatment.

So, melatonin levels, endurance performance, and sleep quality all improved with full-body red light therapy.(Excerpted from：https://www.lighttherapyinsiders.com/red-light-therapy-for-sleep/)