In Brief: Melatonin

Melatonin: May have "deleterious effects" on sleep in certain situations, Benita Middleton, University of Surrey, et al. note in the August 24 issue of The Lancet. The researchers reported the results of two experiments in which groups of men in a closed environment with constant dim light and attenuated sound and temperature took three capsules per day of either 5 mg melatonin or a placebo. The men were told to eat and sleep when they wished. Two out of 10 and two out of six subjects, respectively, showed "highly irregular" sleep cycles during melatonin, but not placebo, treatment. The authors speculated that "the effect may be theoretically explicable if melatonin acts primarily on the timing mechanisms of sleep"...