Poor quality of sleep and delirium are frequent complications of intensive care. The incidence of both complications is high, and evidence-based medicine has significantly demonstrated serious consequences in both cases. More data are available on delirium. While there is significant room for further research on sleep quality impairment, there are also technical limitations of monitoring and diagnosis. This article summarises known data on the epidemiology and risk factors of decreased quality of sleep and delirium in the intensive care setting.