Patients in the intensive care unit suffer from severe lack of sleep associated with loss of normal melatonin secretion pattern

Background: Patients hospitalized in the intensive care unit (ICU) tend to become agitated and confused, and many even develop temporary psychoses (th e ICU syndrome). We wondered whether the regulation of sleep and the secret ion of melatonin is abnormal in ICU patients. Therefore, we studied the ass ociation of sleep-wake pattern in patients hospitalized in the ICU, their m elatonin secretion rates, and profile compared with a control group of pati ents in general medical wards. Methods: Sleep was assessed by actigraphy. Urine was collected every 3 hour s for 24 hours. Melatonin secretion was assessed by measuring the melatonin metabolite 6-sulphatoxy-melatonin by enzyme-linked immunosorbent assay. Results: Actigraphy suggested that the ICU patients lacked normal sleep beh avior for the entire study period, except for occasional short naps. Compar ed with controls, the nocturnal peak of melatonin secretion was absent, exc ept in two patients in the nonventilated group, and showed a flat curve. Conclusions: Our results suggest that lack of sleep is indeed a severe prob lem in ICU patients and is accompanied by impairment of normal melatonin se cretion. The possibility that melatonin administration may prove useful in improving sleep patterns in ICU patients deserves further study.