Sleep Duration of Inpatients With a Depressive Disorder: Associations With Age, Subjective Sleep Quality, and Cognitive Complaints.

Sleep complaints and sleep disturbances are common in depression; however, the association of sleep duration and subjective sleep quality has been rarely investigated. Thus, subjective sleep quality and sleep duration were analyzed in depressed inpatients. Questionnaire data comprising clinical and sleep-related questions were sampled over a one-year period from adult inpatients with depressive syndromes. Sleep duration and items related to sleep quality were analyzed by means of group comparisons (sleep duration categories) and correlation analyses. Data of 154 patients (age 58.2±17.0 years, 63.6% women) were analyzed. Mean sleep duration was 7.2±2.1 h (16.9% of patients were below and 7.1% above age-specific recommendations), 25-40% of patients reported almost always daytime sleepiness, non-restorative sleep, attention deficits, or memory complaints with significant correlations between all variables (P<0.05). Sleep duration and sleep quality indicators showed significant curvilinear associations (quadratic contrast, P<0.05); i.e. extremely low and high sleep durations were associated with unfavorable sleep quality and subjective cognitive impairment. Non-recommended low or high sleep durations occur in a substantial proportion of patients with depression, and both were associated with poor sleep quality and subjectively impaired cognitive functions. Clinicians should be aware of these relationships. During hospitalization, a more individualized sleep-wake schedule should be applied.