Zaleplon increases nocturnal melatonin secretion in humans

Insomnia is the most common sleep condition. Many hypnotics decrease nocturnal melatonin secretion. The aim of this research consists of studying the effect of the hypnotic drug zaleplon on melatonin secretion. Twelve non-smoker drug-free healthy male subjects participated in the study. All participants were normal sleepers and aged 33.2 ± 11.7 years. They orally took 10 mg of zaleplon at 22:00 h in a double-blind, randomized, cross-over design. The study was carried out during two consecutive days in a week-end. Blood samples were extracted at 22:00, 23:00, 24:00, 01:00, 02:00 and 12:00 h. Melatonin was measured by an ELISA assay. All the subjects had a circadian rhythm of melatonin secretion. Zaleplon compared to placebo increased significantly the melatonin levels at 23:00, 24:00 and 01:00 h. No differences in melatonin levels between placebo and zaleplon were found at 12:00, 22:00 and 02:00 h. Zaleplon compared to placebo increased by 46% the Area Under the Curve of melatonin secretion. The present study indicates that zaleplon increases nocturnal melatonin secretion without increasing daytime melatonin levels. We suggest that when clinicians prescribe a hypnotic, the effect on melatonin levels should be another parameter to be taken into account.