Sleep in the critically ill patient

The sleep of intensive care unit (ICU) patients is remarkably disrupted. Several studies, employing both subjective and objective measures of sleep quality, have demonstrated that critically ill patients exhibit severe sleep fragmentation and reduced restorative sleep, particularly a suppression of rapid eye movement (REM) sleep. The cause of sleep disruption in the ICU appears to be multifactorial and includes both the patients' acute and chronic illnesses and factors that are unique to the ICU environment. Noise has been a significant focus of investigation, and the effects of medications, light, and patient-care activities have also been examined. Several questions remain to be answered so that caregivers can improve sleep in ICU patients, including the relative contribution of different sleep-disrupting factors and possible changes in patient susceptibility to these factors over time.