Blue Light May Help Heal Mild Traumatic Brain Injury, Says Study

Early morning blue light exposure therapy may aid the healing process of people impacted by mild traumatic brain injury, according to a study. Mild traumatic brain injuries, or concussions, are often the result of falls, car accidents and sports participation. Among other threats, military personnel can also experience mTBI from exposure to explosive blasts.

"Daily exposure to blue wavelength light each morning helps to re-entrain the circadian rhythm so that people get better, more regular sleep," said William D. Killgore, a psychiatry professor at the University of Arizona in the US. "This is likely true for everybody, but we recently demonstrated it in people recovering from mild traumatic brain injury, or mTBI.

"That improvement in sleep was translated into improvements in cognitive function, reduced daytime sleepiness and actual brain repair," Killgore said. Shockwaves strike the soft tissue of the gut, and push a burst of pressure into the brain, causing microscopic damage to blood vessels and brain tissue, Killgore said.

Those with a concussion or mTBI might momentarily become disoriented, or even briefly lose consciousness following the injury. However, loss of consciousness doesn't always happen and many people who sustain a concussion are able to walk it off without realising they have a mild brain injury, according to Killgore.

Few effective treatments for mTBI exist, according to the study published in the journal Neurobiology of Disease. "About 50 per cent of people with mTBI also complain that they have sleep problems after an injury," Killgore said.

Recent research has shown that the brain repairs itself during sleep, so Killgore and his co-authors sought to determine if improved sleep led to a faster recovery. In a randomised clinical trial, adults with mTBI used a cube-like device that shines bright blue light -- with a peak wavelength of 469 nanometre -- at participants from their desk or tables for 30 minutes early each morning for six weeks.

Control groups were exposed to bright amber light, the researchers said. "Blue light suppresses brain production of a chemical called melatonin," Killgore said.

"You don't want melatonin in the morning because it makes you drowsy and prepares the brain to sleep. When you are exposed to blue light in the morning, it shifts your brain's biological clock so that in the evening, your melatonin will kick in earlier and help you to fall asleep and stay asleep," Killgore said. People get the most restorative sleep when it aligns with their natural circadian rhythm of melatonin -- the body's sleep-wake cycle associated with night and day.

"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," he said. 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, researchers said.

Participants improved their 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, the researchers said.

"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.