Photobiomodulation and Sleep: Can Light Help Us Sleep Better?
Sleep is much more than a period of inactivity. While we sleep, the body restores energy, supports tissue repair, regulates immune and hormonal activity, and consolidates memories. The brain itself moves through carefully coordinated changes in metabolism and neural activity throughout the night.
A new systematic review and meta-analysis asks an intriguing question: could photobiomodulation help support sleep quality?
Researchers analyzed five randomized controlled trials involving a total of 240 participants. When the results were combined, photobiomodulation was associated with an average 1.25-point improvement on the Pittsburgh Sleep Quality Index compared with sham treatment, and the overall result reached statistical significance.¹
What Does Light Have to Do With Sleep?
One possible connection begins with cellular energy. Photobiomodulation uses specific wavelengths of light to influence biological processes. One of its best-studied interactions involves cytochrome c oxidase, an enzyme within the mitochondria. Mitochondria produce ATP, the form of energy our cells use to carry out their work.
Photobiomodulation may influence this energy-production process while also affecting oxidative stress, nitric oxide, circulation, and tissue oxygenation.¹ These mechanisms are particularly interesting when it comes to the brain. Sleep and wakefulness involve major shifts in brain metabolism, and healthy sleep depends on the brain’s ability to regulate its energy needs throughout the day and night.
Blood Flow, Oxygen and Brain Activity
The review also points to neuroimaging research suggesting photobiomodulation can influence cerebral oxygenation and activity within brain networks involved in sleep regulation.
Studies outside the five sleep trials have measured changes in prefrontal cortical activity, functional connectivity, and cerebral oxygenation following photobiomodulation.¹ The prefrontal cortex plays an important role in maintaining healthy sleep-wake patterns, and disruptions to these networks have been observed in people with insomnia. Researchers are therefore investigating whether improving cellular metabolism and cerebral circulation could indirectly help support the systems involved in sleep.
Another Clue: Adenosine and Sleep Pressure
There may also be a connection with specialized brain cells called astrocytes. Astrocytes help regulate brain metabolism and communicate with surrounding neurons. They are also involved in signalling pathways connected to adenosine.
Adenosine builds up while we are awake. As its levels rise, so does our biological drive to sleep. This accumulating pressure is part of what makes us increasingly tired the longer we remain awake.
Experimental research suggests photobiomodulation may influence astrocytic metabolism and adenosine-related signalling.¹ This has not yet been shown to be the mechanism behind the sleep improvements seen in clinical trials, but it gives researchers another plausible connection between light, cellular energy, and the regulation of sleep.
What Did the Clinical Research Find?
The five randomized trials included people with a variety of health conditions, including chronic insomnia, depression, kidney disease requiring dialysis, and other conditions associated with disturbed sleep. The treatment methods also varied considerably.
Even with those differences, the pooled analysis found a statistically significant improvement in self-reported sleep quality in participants receiving photobiomodulation compared with sham treatment.¹
That makes the result interesting, particularly because it emerges across several different clinical populations. At the same time, researchers do not yet have a single standardized photobiomodulation protocol for sleep. Different wavelengths, doses, treatment locations, and schedules were used across the studies.
The authors therefore describe the evidence as preliminary and emphasize the need for larger trials using more consistent treatment protocols and objective sleep measurements.
A Growing Area of Sleep Research
Photobiomodulation is not currently an established treatment for insomnia, and the new research does not replace proven approaches to sleep care. What it does provide is another intriguing piece of the biological puzzle.
Red light influences mitochondrial energy production, cerebral circulation, oxidative stress, and networks involved in regulating sleep and wakefulness. Now, randomized clinical research is beginning to suggest that these biological effects may also translate into measurable changes in how people experience their sleep.
For something we spend roughly a third of our lives doing, there is still an enormous amount to learn about sleep.
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We’ll continue following the research as scientists learn more about the relationship between photobiomodulation, brain function, cellular energy, and rest. Curious about how light therapy could complement your broader wellness routine? Connect with the RegenClinic team. We’re always happy to answer your questions.
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