Sleep is an essential biological function that has physiological, behavioral and temporal characteristics. It is regulated by homeostatic and circadian processes. The knowledge of the importance of sleep and the adverse effects of sleep deprivation has grown in an exponential manner over the last few years. Although approximately 5.7 million adults are cared for in an intensive care unit (ICU) annually in the U.S, and despite the growing awareness of the potential importance of sleep in the ICU, many questions about the nature of sleep, the predictors and consequences of sleep disruption and the efficacy of sleep promoting interventions in critically ill patients remain unanswered. This grant proposes the following Specific Aims: Specific Aim 1: Determine feasibility of acquiring high quality portable polysomnographic (PSG) data over a 24-hour period among patients age 60 and older in the medical intensive care unit (MICU) who have respiratory failure requiring mechanical ventilation. Feasibility will consist of three components: 1. Patient, family and nursing acceptance of PSG in critically ill patients. 2. Ability to perform a 24-hour portable PSG in mechanically ventilated patients in the MICU. 3. Ability to obtain EEG data to examine sleep latency, sleep stages, and sleep duration. Specific Aim 2: Describe the severity of sleep disruption over a 24-hour period among patients age 60 and older admitted with respiratory failure who are mechanically ventilated. For the purpose of hypothesis generation we will track both predisposing and precipitating factors which may contribute to sleep disruption. Specific Aim 3: Describe sleep architecture and the distribution of sleep over a 24-hour period among patients age 60 and older admitted with respiratory failure who are mechanically ventilated. Sleep disruption has been shown to have important effects on immune function, glucose metabolism and cognitive function, all of which may contribute to poor outcomes from critical illness. More importantly sleep is a potentially modifiable factor in the intensive care unit. Once accurate sleep data is collected we can begin to examine how sleep disruption, shifts in sleep stages, and alterations in circadian rhythms impact critical care outcomes including delirium. The information obtained in this pilot study will also be useful for designing studies that examine predisposing and precipitating risk factors for sleep disruption in critical illness and the effect of using sedative-hypnotic medications on sleep patterns. PUBLIC HEALTH RELEVANCE: There are 5.7 million adults admitted to intensive care units (ICU) each year in the U.S. Little is known about the impact of sleep in the ICU. The goal of the study is to examine the feasibility of using portable polysomnography to study sleep in older patients admitted to a medical ICU who require mechanical ventilation. The ultimate goal of this research is to better understand factors which lead to impaired sleep in critical illness, the importance of sleep on outcomes from ICU care and to develop interventions to promote sleep in a critical care environment.