Abnormal nocturnal melatonin secretion and disordered sleep in abstinent alcoholics.

BACKGROUND Alcoholic patients show prominent disturbance of sleep as measured by electroencephalogram, with difficulties in the onset and maintenance of sleep. Given the role of melatonin in the regulation of the sleep-wake cycle, this study examined the relationship between nocturnal expression of melatonin and sleep in alcoholics as compared with control subjects. METHODS Alcoholic patients (n = 11) and comparison control subjects (n = 10) underwent all-night polysomnography and serial blood sampling every 30 min from 10:00 PM to 6:30 AM for measurement of circulating levels of melatonin and cortisol. RESULTS Coupled with prolonged sleep latency, alcoholics showed lower levels of melatonin during the early part of the night and a delay in the onset of the nocturnal plateau or peak value of melatonin as compared with control subjects. The nocturnal delay of melatonin correlated with prolonged sleep latency. Circulating levels of cortisol were lower during the early part of the night and higher in the late part of night in the alcoholics as compared with the control subjects. CONCLUSIONS A delay in the nocturnal rise of melatonin may contribute to disordered sleep in chronic alcoholics, with implications for the use of melatonin in the treatment of insomnia in recovering alcoholics.