Sleep disruption results in numerous deleterious effects on an already fragile and disturbed physiology. Pulmonary consequences include decreased functional vital capacity, blunted hypercapnic and hypoxic responses, and decreased respiratory muscle endurance. As a result of the autonomic imbalances that follow sleep deprivation, increased hypertensive episodes, more frequent arrhythmias, and increased risk of acute myocardial ischemia have been described. In addition, sleep deprivation promotes a negative nitrogen balance, increased restingenergy expenditure, and immunological depression via suppression of antibody and cell-mediated responses. Most obvious to the physician, however, are the neurocognitive sequelae. Delirium, anxiety, hallucinations, and mood disorders have been associated with sleep deprivation in the ICU. In fact, healthy volunteers subjected to ICU-like sleep disturbances develop irritability, disorientation, and slurred speech.

Nonpharmacologic options to improve sleep hygiene include placing patients in private or single rooms with several windows, minimizing nighttime conversations by hospital personnel, placing alarms
outside of patient rooms, and scheduling baths, linen changes, routine laboratory draws, and radiographs during the daytime. Studies that have evaluated the impact of noise reduction in the ICU have noted marked improvement in sleep quality. Improved REM sleep has been demonstrated with the implementation of earplugs in ICU patients. Additionally, lights should be turned off or dimmed at night to maintain circadian light cycles. Conversely, keeping the lights on during the daytime has been shown to reset circadian cycles and improves sleep at night, specifically in the elderly. In the high-risk population of elderly ICU patients, physical therapy and increased activity have been shown to promote sleep with shorter latency and deeper levels achieved.