EFFECTS OF EXOGENOUS MELATONIN ADMINISTRATION AND WITHDRAWAL IN 5 PATIENTS WITH RAPID-CYCLING BIPOLAR DISORDER

Background: The ready availability of exogenous melatonin means that i ts use in patients with mood disorders is probably not uncommon. Nonet heless, few controlled trials of exogenous melatonin in these patients have been conducted. Method: Five patients with rapid-cycling DSM-III -R bipolar disorder were treated with melatonin 10 mg q.d. at 10:00 p. m. for 12 weeks. Melatonin was added to a stable regimen of medication and administered in a double-blind, placebo-controlled fashion. Resul ts: Melatonin administration had no positive effects. One patient deve loped a free-running (unentrained) sleep-wake cycle after melatonin wi thdrawal. In addition, in both this and a second patient, there is evi dence that the administration of exogenous melatonin may have suppress ed the secretion of endogenous melatonin. Conclusion: The administrati on of melatonin had no significant effects on mood or sleep. However, melatonin withdrawal delayed sleep onset time and may have had some mi ld mood-elevating effects.