Outcomes/Effectiveness Research

Light therapy appears to improve sleep, mood, and energy among women with nonseasonal depression

Light therapy effectively treats seasonal affective disorder (SAD), a depression that strikes only in the fall and winter, when there is less daylight. A new study, supported by the Agency for Healthcare Research and Quality (HS00093), shows that light therapy can also improve sleep, mood, and energy among women with depression who do not suffer from SAD. Geoffry W. McEnany, R.N., Ph.D., C.S., of the University of Massachusetts, and Kathryn A. Lee, R.N., Ph.D., F.A.A.N., of the University of California, San Francisco studied 29 premenopausal and postmenopausal women who were diagnosed with major depressive disorder (MDD) and were not taking psychotropic drugs or hormone replacement therapy during the study. Sixteen women wore a light visor, which had proven successful in trials of persons diagnosed with SAD, during the first waking hour for one month. The placebo group of 13 women wore a pair of glasses that filtered out light one hour before bedtime.

The light intensity of the light visor was set at 2,500 lux. This light appears bright relative to typical indoor lighting of 150 lux, but dim compared to outdoor light, which can reach 100,000 lux. Both the severity and symptoms related to depressed mood declined significantly in the light-treated group but not in the placebo group. The depression scores of the light-treated group also continued to drop on day 29 to below that of day 15.

The 24-hour mean body temperature and time to sleep onset declined significantly and level of energy increased significantly in the treatment group, but not in the placebo group. This is important because the lower the 24-hour mean temperature, the shorter the time to sleep onset, the better the sleep efficiency, and higher the level of energy. The researchers speculate that depression changes normal thermoregulatory and neuroendocrine rhythms, which the light therapy corrects.

For more information, see "Effects of light therapy on sleep, mood, and temperature in women with nonseasonal major depression," by Drs. McEnany and Lee, in the August/September 2005 Issues in Mental Health Nursing 26, pp. 781-794, 2005.

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