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 r eflections of subjective sleep quality in patients with liver cirrhosi s. 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 hepati c encephalopathy. Plasma melatonin levels measured every 30 minutes fo r 24 hours by radioimmunoassay. Sleep diaries kept for 1 week before a dmission. Results: Patients with cirrhosis had markedly elevated melat onin levels during daytime hours; in addition, the time of onset of me latonin increase and the time at which melatonin levels peaked were co nsistently 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.