Sleep disturbances in critically ill patients

Sleep is an essential part of life with many important roles which include immunologic, cognitive and muscular functions. Of the working population 20% report sleep disturbances and in critically ill patients an incidence of more than 50% has been shown. However, sleep disturbances in the intensive care unit (ICU) population have not been investigated in detail. Sleep disturbances in ICU patients have a variety of reasons: e.g. patient-related pathologies like sepsis, acute or chronic pulmonary diseases, cardiac insufficiency, stroke or epilepsy, surgery, therapeutical interventions like mechanical ventilation, noise of monitors, pain or medication. Numerous scales and questionnaires are used to quantify sleep and the polysomnogramm is used to objectify sleep architecture. To improve sleep in ICU patients concepts are needed which include in addition to pharmacological treatment (pain reduction and sedation) synchronization of ICU activities with daylight, noise reduction and music for relaxation. In order to establish evidence-based guidelines, research activities about sleep and critical illness should be intensified. Questions to be answered are: 1) Which part of sleep disturbances in critically ill patients is directly related to the illness or trauma? 2) Is the grade of sleep disturbance correlated with the severity of the illness or trauma? 3) Which part is related to the medical treatment and can be modified or controlled? In order to define non-pharmacological and pharmacological concepts to improve sleep quality, studies need to be randomized and to include different ICU populations. The rate of nosocomial infections, cognitive function and respiratory muscle function should be considered in these studies as well. This will help to answer the question, whether it is useful to monitor sleep in ICU patients as a parameter to indicate therapeutical success and short-term quality of life. Follow-up needs to be long enough to detect adverse effects of withdrawal symptoms after termination of analgesia and sedation or delirium.