Al Lewy, M.D., Ph.D.
07/20/2009 - About 100,000 blind people in the United States suffer from sleep disorders caused by their brains’ inability to distinguish between darkness and light. In the early 1980s, Al Lewy, M.D., Ph.D., Professor in the Department of Psychiatry, established that exposure to bright light can reset out-of-phase body clocks in the sighted.
About 100,000 blind people in the United States suffer from sleep disorders caused by their brains’ inability to distinguish between darkness and light. Their bodies run not on a 24-hr time period, but on daily cycles where sleep comes up to an hour later each day. Left unchecked, these disordered sleep rhythms can become one of the most burdensome aspects of loss of sight.
In the early 1980s, Al Lewy, M.D., Ph.D., Professor in the Department of Psychiatry, established that exposure to bright light can reset out-of-phase body clocks in the sighted. This treatment, however, was not an option for the totally blind.
Dr. Lewy instead applied his work on the role of melatonin in sleep to the problem of regulating sleep patterns in the blind. With Robert Sack, M.D., Professor Emeritus, Department of Psychiatry, and Jonathan Emens, M.D., Assistant Professor, Department of Psychiatry, Dr. Lewy established a protocol of using selective dosing of melatonin – in terms of quantity and when in the circadian cycle the dose is administered – to entrain blind patients with body-clock cycles of as much as 24.9 hours to the 24-hr sleep-wake cycle experienced by most people.
“We were failing to entrain patients with doses of 5 milligrams (mg) of melatonin and initially assumed that all we had to do was increase the dosage,” said Lewy. While a 10mg dose did prove effective in most of the subject patients, it still failed to entrain one patient whose body clock was keeping a 25-hour day. From that one patient, Dr. Lewy determined that the size of the dose was less important than the time in the circadian cycle at which it was given. He has subsequently used this discovery to regulate the rhythms of all the subjects who initially responded to the 10mg dose.
“This is important because large doses of melatonin during waking hours can have sleep-inducing side-effects in about a third of the population,” said Dr. Lewy. “The more you can minimize these side-effects with effective micro-doses, the better the therapy will be to a wider population.”
The accumulated knowledge delivered by Lewy’s thirty years of research in melatonin regulation has now defined a new field – Chronobiology. Chronobiologists measure the sleep cycles of any blind or sighted individual, and offer bright light therapy or micro doses of melatonin to regulate these cycles where they deviate from the 24-hour norm.
Dr. Lewy is now focusing his attention on mental health conditions in which sleep disorders are prevalent. “We’re starting to look at children and adults with Attention Deficit Hyperactivity Disorder, non-seasonal depression and other psychological disorders. Regulating their sleep is not a cure for their condition, but it might help mitigate the contribution that disrupted sleep makes to the severity of their symptoms.”
Alfred Lewy, M.D., Ph.D. is the Richard H. Phillips Professor of Biological Psychiatry in the department of psychiatry; senior vice chair of the department; and director of the Mood Disorders Research Laboratory.