 Circadin is a newly developed slow release galenic formulation of melatonin, producing overall levels of melatonin comparable to those observed in a control population, when administered to patients with deficiency in melatonin; thus it deserves more clinical and paraclinical investigations for establishing efficacy in inducing and maintaining sleep and for safety. Since, on the one hand, the endogenous substance melatonin has beneficial effects on sleep in man and, on the other hand, there is a decrease in melatonin secretion in elderly people, substitution therapy in elderly insomniacs would be a desirable therapy. 