This literature review shows that sleep is important for healing and survival of critical illness (Richardson et al., 2007; Straham and Brown, 2004). Sleep deprivation impinges on recovery, ability to resist infection, brings about neurological problems such as delirium, respiratory problems because it weakens upper air way muscles thus prolonging the duration of ventilation, ICU stay and complicating periods just after extubation (Friese, 2008; Parthasarathy and Tobin, 2004). Noise, pain and discomfort (Jacobi et al., 2002; Honkus, 2003) modes of ventilation and drugs have been cited as causes of sleep deprivation in critically ill patients (Friese, 2008; Parthasarathy and Tobin, 2004). The inability of nurses to accurately assess patients' sleep has also been cited as a concern while polysonography has been cited as the most effective way of assessing patients' sleep despite the difficulties associated with it. While some of these causes of sleep disruption can not be easily alleviated, every effort must be made to promote REM and SWS sleep. More research is needed to find solutions to sleep disruption in ICU. More research is needed to ascertain the impact of mechanical ventilation on sleep disruption and more focused ways of sleep assessment are needed. Nurses need to minimise disruptions by clustering their care at night in order to allow patients to have the much needed REM sleep. Furthermore, more specific way of sleep assessment in the critically ill.