Darkness Disturbs Sleep of the Blind

B O S T O N, Oct. 11 -- For the 200,000 Americans who are completely blind, darkness is a constant, but sleep is often disturbed.

Without light cues that the rest of us rely on to synchronize our body clocks, as many as half of these blind people may have difficulty getting sleep schedules in step with a 24-hour cycle and may suffer sleep disorders as a result, researchers say.

But a new study shows that a daily dose of melatonin may be able to help reset a blind person’s unregulated body clock to a daily schedule, making it easier to rise and shine. The research, from a team of doctors at Oregon Health Sciences University in Portland, is in the Oct. 12 issue of the New England Journal of Medicine.

According to Dr. Alfred Lewy, a co-author of the study, this finding can also be applied to those with sight who experience shift changes at jobs, jet lag, daylight-saving time adjustment problems, winter depression and the “Monday Blues.”

Melatonin Revisited Melatonin is a hormone produced every evening by the brain’s pineal gland. Apparently, the chemical helps facilitate the onset of sleep. Darkness serves as a cue for the body to secrete melatonin into the blood stream and light serves to suppress it. Melatonin production also drops with age, possibly causing the elderly to get less sleep.

In recent years, melatonin has been hailed as a “wonder drug,” with proponents claiming it could be used for everything from fighting aging to improving one’s sex drive, without evidence from human studies, Lewy says. Because melatonin is a naturally occurring hormone, companies sell it as an over-the-counter dietary supplement — without any regulation by the Food and Drug Administration or thorough testing of any potential health claims.

“This study cuts through all the hype and spurious claims for melatonin a few years ago, and establishes its main use in humans: to help people with body clock disorders,” Lewy says.