Setting the Body Clock in the Dark

From the WebMD Archives


"Even on small doses of melatonin, the sleep pattern remained normal," James E. Jan, MD, tells WebMD. "This study has great clinical importance for those unfortunate blind individuals who suffer from this severe, chronic sleep disorder throughout their lives," says Jan, director of the visually impaired program at the British Columbia's Children's Hospital in Vancouver, British Columbia. He was not involved in the study.

Of approximately two million legally blind people in the U.S., about 200,000 may have a sleep disorder "that for some is the second most burdensome aspect of being blind," Lewy says.

Blind study participants offer a unique opportunity to researchers "because their lack of light input allows us to study the basic physiology of the body clock unperturbed by the light/dark cycle," says Lewy. "What we learn about their clocks we can generalize to sighted people."

Sleep disorders in sighted people that may respond to melatonin include jet lag, "Monday blues," and seasonal affective disorder, or depression related to less daylight in winter. Melatonin may regulate sleep in these conditions by setting the body clock back to normal. It may even correct sleep problems related to working night shifts or adjusting between daylight-saving time and standard time.

Melatonin has been widely used as a nutritional supplement without any reports of serious side effects, and this study shows that even very low doses can be helpful. However, patients first starting melatonin for sleep disorders may need higher doses, which should be supervised by a physician, Lewy explains.

"We still do not know the side effects of chronic or lifetime melatonin [use]," Honma says.

For all you morning larks who bounce out of bed when the whole house is still snoring, or for you night owls pacing the halls when everyone else has gone to bed, melatonin might be something to consider. As with all nutritional supplements, caution and good judgment are needed, and melatonin may not work for everyone.

"About 10% to 15% of patients taking melatonin to induce sleep may actually feel more awake than before," warns George A. Bubenik, MD, associate professor of zoology at the University of Guelph in Guelph, Ontario.