Assessment of sleep patterns, energy expenditure and circadian rhythms of skin temperature in patients with acute coronary syndrome

BACKGROUND There is no simple and practical way to monitor sleep patterns in patients in acute care units. We designed this study to assess sleep patterns, energy expenditure and circadian rhythms of patients' skin temperature in the coronary care unit (CCU) utilizing a new portable device. MATERIAL/METHODS The SenseWear Armband (SWA) was used to record sleep duration, distribution over 24 hr, energy expenditure and the circadian rhythms of skin temperature in 46 patients with acute coronary syndrome (ACS) for the first 24 hr in the CCU and upon transfer to the ward. An advanced analysis was used to extract and compare data associated with the above variables in the two settings. RESULTS Patients in the CCU had a reduced night's sleep duration (5.6 ± 2.2 hr) with more frequent and significantly shorter night sessions (p=0.015) than patients in the ward. Energy expenditure and METs (metabolic equivalents of a task) were significantly lower in the CCU than in the ward. However, the midline-estimating statistic of rhythm (MESOR) and acrophase for skin temperature did not exhibit any significant difference between the two settings. CONCLUSIONS Patients with ACS have sleep fragmentation and shorter nocturnal sleep duration in the CCU compared to the ward. On the other hand, there was no difference in the circadian rhythms of skin temperature between patients in the CCU and the general wards.