Reliability of a Scale Assessing Depressed Mood in the Context of Sleep.

The current study assessed the reliability of Kandel & Davies mood scale with and without sleep-related items. 178 Brown University first-year students (mean age=18.1 years; 108 females) completed online biweekly surveys after weeks 2, 6, 8, and 10 and on 2 consecutive days after weeks 4 and 12 of their first semester. The scale was examined as a 1) full 6-item scale, 2) 5-item scale excluding the sleep item, and 3) 4-item scale excluding the sleep and tired items. Intraclass correlations (ICC) values for consecutive-day assessments and 6 biweekly surveys were similar and not a function of the weeks evaluated. Total-item correlations and inter-measure correlations with the Center for Epidemiologic Studies - Depressed Mood Scale (CES-D) supported the removal of the sleep-related items from the 6-item scale. These analyses confirm the reliability of the original Kandel and Davies depressed mood scale as well as without the sleep-related items.