Sleep and recovery from critical illness and injury: A review of theory, current practice, and future directions*

Sleep deprivation and disruption are particularly prevalent in patients cared for in the critical care environment. Although numerous observational studies during the past several decades have demonstrated that sleep in patients cared for in ICUs is highly abnormal, little is known about the effects of poor sleep quality on outcomes from critical illness or injury. Reasons for sleep deprivation during recovery from illness and injury in the ICU are multifactorial. Major contributing factors in this patient population are type and severity of underlying illness, the pathophysiology of acute illness/injury, pain from surgical procedures, and perhaps most importantly, the ICU environment itself. Sleep in ICU patients is characterized by prolonged sleep latencies, sleep fragmentation, decreased sleep efficiency, frequent arousals, a predominance of stage 1 and 2 nonrapid eye movement sleep, decreased or absent stage 3 and 4 nonrapid eye movement sleep, and decreased or absent rapid eye movement sleep. Optimizing patient comfort and ensuring that patients achieve adequate restorative sleep while cared for in the ICU is an arduous task. However, environmental alterations in the ICU may reliably improve sleep quality and subsequently alter outcomes during recovery from critical illness and injury.