Diurnal variation of melatonin and cortisol is maintained in non-septic intensive care patients

Objective To study the diurnal variation of melatonin and cortisol in critically ill patients and to assess whether the severity of organ dysfunction, sedation and sympathetic activity correlate with the production of these hormones. Design Prospective clinical study. Setting Surgical intensive care unit in a university hospital. Patients Forty non-septic patients without brain injury and treatment with adrenergic agonists or corticosteroids. Twenty-five of the patients were sedated with benzodiazepines. Interventions None. Measurements and results The pattern of melatonin production was monitored by the determination of 6-sulphatoxymelatonin (aMT6s) in urine. The 12-h aMT6s excretions at nights (11.8 ± 8.9 μg, mean ± SD) were higher than in the daytime (6.8 ± 7.5 μg; P