Sleep problems are common among psychiatric patients. A survey of 560 patients in the Netherlands found that 36% of them perceived themselves as having a sleep problem. The patients filled in the Pittsburgh Sleep Quality Index which found that 66% of them could be classified as bad sleepers. 49% of the sample used sleep medication one or more times a week.
de Niet, G.J. ... [et al] - Perceived sleep quality of psychiatric patients Journal of Psychiatric and Mental Health Nursing August 2008, 15(6), 465-470