DISRUPTION OF THE DIURNAL RHYTHM OF PLASMA MELATONIN IN CIRRHOSIS

Objectives: To assess 24-hour plasma melatonin profile as a marker of output rhythm from the circadian clock and to study sleep diaries as reflections of subjective sleep quality in patients with liver cirrhosis. Design: Prospective cohort study. Setting: Clinical research center in a university hospital. Patients: Seven patients with cirrhosis but not alcoholism and seven age-, sex-, and education-matched controls. Measurements: Neuropsychological testing to confirm subclinical hepatic encephalopathy. Plasma melatonin levels measured every 30 minutes for 24 hours by radioimmunoassay. Sleep diaries kept for 1 week before admission. Results: Patients with cirrhosis had markedly elevated melatonin levels during daytime hours; in addition, the time of onset of melatonin increase and the time at which melatonin levels peaked were consistently and significantly delayed in these patients. Sleep diaries indicated more nocturnal awakenings and more frequent daytime naps in patients with cirrhosis. Conclusion: Disruption of the diurnal rhythm of melatonin may reflect alterations of circadian function that could contribute to the disturbances of the sleep-wake cycle frequently seen in patients with cirrhosis.