Insomnia and major depressive episodes (MDE) have each been associated with quality of life (QOL) deficits. In this study we examined insomnia as an independent predictor of QOL deficits during MDE, and used a secondary analysis of cross-sectional data. The study was based at the inpatient psychiatric ward and included 88 adults (mean age 53; 78% women). We assessed insomnia severity with the 21-item Hamilton Rating Scale for Depression (HRSD) and the Beck Depression Inventory (BDI). Measurements of QOL in the week prior to admission included activities of daily living (ADLs), instrumental ADLs (IADLs), daily living and role functioning, and relation to self and colleagues (the last two both subscales of the Basis 32). Linear regression models used the insomnia items as independent variables and the QOL measures as the dependent variables, after adjusting for age and nonsleep related depression severity. The results showed that 93% of patients endorsed insomnia on the observer-rated HRSD, and 97% endorsed sleep disturbance in the self-rated BDI. However, the insomnia items on the HRSD and BDI showed poor concurrent validity. Increasing severity of insomnia on the HDRS was associated with better QOL, while increasing severity of insomnia on the BDI was associated with worse QOL. We conclude that the BDI and HRSD do not produce equivalent measures of insomnia severity in depressed inpatients, and each insomnia measure has a unique relationship with QOL.
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