By Bower, Bruce
Science News , Vol. 137, No. 21
Bright-light therapy expands its horizons
Over the last decade, researchers have found that daily doses of bright light markedly improve the mood of people with recurring depressions that emerge only in winter (SN: 5/21/88, p.331). But light therapy also offers rays of hope for those suffering from nonseasonal depression, as well as for chronic "night owls" whose inability to fall asleep until the wee hours of morning causes them serious daytime problems, according to two preliminary studies described at last week's annual meeting of the American Psychiatric Association in New York City.
"Light therapy is more versatile than anyone expected," concludes Norman E. Rosenthal of the National Institute of Mental Health (NIMH) in Bethesda, Md., who coauthored one of the new reports.
In a study directed by Daniel F. Kripke of the University of California, San Diego, bright light benefited 25 male veterans hospitalized for severe, nonseasonal depression. The men stayed in a room illuminated with 1,600 watts of bright white light between 8 p.m. and 11 p.m. every night for one week. Another 26 depressed men received similar treatment with dim red light. No one in the study was taking antidepressant medication.
Compared with the dim-light group, men exposed to bright light reported an 18 percent reduction in depression symptoms at the end of the week.
Although researchers have yet to test the long-term effect of light therapy, the one-week results offer encouragement, especially since it takes several weeks for antidepressant drugs to begin to ease depression. Combining bright lights with drug treatment may speed recovery from a bout of depression, Kripke asserts.
The San Diego scientists are not sure why light therapy worked with nonseasonal depression. But Rosenthal suggests that the circadian timing system that governs sleepiness, hormone levels and other daily cycles of the body and behavior may be out of sync in nonseasonal depression. …