While blue light from computer screens and phones often gets a bad rep, psychiatry professor Scott Killgore’s new study suggests that’s not the case—as long as the timing is correct.
Killgore and his team at the University of Arizona successfully used blue light exposure therapy to help re-train the circadian rhythm of people suffering from a recent mild traumatic brain injury, or a concussion usually caused by mild head impact such as a sports injury or a car accident.
Based on other published research, Killgore and his co-authors designed a study to determine if improved sleep led to a faster recovery for those with mTBI. In a randomized clinical trial, adults with mTBI used a cube-like device that shines bright blue light (with a peak wavelength of 469 nm) for 30 minutes early each morning for six weeks. Meanwhile, control groups were exposed to bright amber light. As a result of the blue light treatment, participants fell asleep and woke an average of one hour earlier than before the trial and were less sleepy during the daytime.
"The circadian rhythm is one of the most powerful influences on human behavior," Killgore said. "Humans evolved on a planet for millions of years with a 24-hour light/dark cycle, and that's deeply engrained in all our cells. If we can get you sleeping regularly, at the same time each day, that's much better because the body and the brain can more effectively coordinate all these repair processes."
In this study, blue light treatment in the morning helped suppress brain production of melatonin, the naturally occurring chemical that jumpstarts the body’s sleep process. The light helped shift the brain’s biological clock so that in the evening, an individual’s melatonin kicked in earlier, resulting in earlier and better sleep.
Participants in the study also saw improved speed and efficiency in brain processing and showed an increase in volume in the pulvinar nucleus, an area of the brain responsible for visual attention. Neural connections and communication flow between the pulvinar nucleus and other parts of the brain that drive alertness and cognition were also strengthened.
"We think we're facilitating brain healing by promoting better sleep and circadian alignment, and as these systems heal, these brain areas are communicating with each other more effectively. That could be what's translating into improvements in cognition and less daytime sleepiness," Killgore said.
People get the most restorative sleep when it aligns with their natural circadian rhythm of melatonin. As it turns out, this kind of sleep is also the best for quickly healing mild brain injuries.
Killgore and his team plan to continue their research to see if blue light improves sleep quality and how light therapy might affect emotional and psychiatric disorders. Additionally, in future studies, Killgore intends to see if correctly timed blue light exposure can benefit uninjuried people, as well.
Photo: Research technician Cami Barnes tests a blue light device. Credit: Killgore/University of Arizona