SLEEP QUALITY AND LIFE SATISFACTION IN SEVERELY DEPRESSED INDIVIDUALS

Abstract

Life satisfaction decreases as depression severity increases, but we wanted to explore how sleep quality factors into this relationship. Can higher sleep quality restore an individual’s level of life satisfaction, especially in those who are severely depressed? To answer this question, we ran a regression of life satisfaction on sleep quality among individuals of minimal (n=2178), mild (n=624), moderate (n=667), and severe (n=609) depression, using data we collected during a 13-month online cross-sectional study on mental health (April 2020-April 2021). This yielded a separate regression analysis for each depression severity group, with the total score on the Satisfaction With Life Scale as the dependent variable, and responses to Item 6 on the Pittsburgh Sleep Quality Index (PSQI)—“During the past month, how would you rate your sleep quality overall?” ranging from “very bad” (coded as 1) to “very good” (coded as 4)—as the independent variable. Our findings showed a significant positive correlation between total SWLS score and PSQI sleep quality score in minimally, mildly, moderately, and severely depressed groups (Rminimal=.187, p<.001; Rmild=.129, p=.001; Rmoderate=.180, p<.001; Rsevere=.438, p<.001). However, the R square value was far larger in the severely depressed group than it was in all other groups (R2adj/severe=.191; versus R2adj/minimal=.034, R2adj/mild=.015, and R2adj/moderate=.031). These findings indicate that better sleep quality more strongly predicts higher life satisfaction in severely depressed individuals, compared to those who are not severely depressed. Thus, interventions that focus directly on improving sleep quality would likely be a meaningful approach to increase life satisfaction in severely depressed individuals.