Assessment of sleep problems with the Insomnia Severity Index (ISI) and the sleep item of the Patient Health Questionnaire (PHQ-9) in cancer patients

The ISI is effective in detecting sleep problems in cancer patients. Normative studies with the ISI would be helpful for assessing ISI mean scores. Sex differences should be taken into account when groups of patients are compared. The sleep item of the PHQ-9 can be used in epidemiological studies.