Lack or disturbances of sleep are major problems in patients staying in intensive care unit (ICU) due to the particular environment. The noises, lack of circadian rhythm of light lead to progressive deafferentation. The patients are then at risk of immune deficiencies, agitation and confusion states, cognitive troubles that may be associated to increased morbidity and mortality in the short and long term. Thus, improvement of the sleep of the ICU patients may impact non only during the ICU stay but also on their future quality of life.