0304 Sleep Quality and Life Satisfaction in Severely Depressed Individuals

Abstract Introduction Better sleep quality correlates with higher life satisfaction. However, the strength of this relationship in the severely depressed population has yet to be explored. We hypothesized that better sleep quality would more strongly predict higher life satisfaction in severely depressed individuals, as compared to those who are not severely depressed. Methods We conducted a 13 month cross-sectional study on mental health during the main months of the COVID-19 lockdown (April 2020-April 2021). We included the Pittsburgh Sleep Quality Index (PSQI), the Beck Depression Inventory (BDI), and the Satisfaction With Life Scale (SWLS) in months 1 (N=1013), 4 (N=1043), 7 (N=1022), and 10 (N=1011). Using this data, we ran a linear regression between total SWLS scores, which increase with higher life satisfaction, and their responses to item six on the PSQI: “During the past month, how would you rate your sleep quality overall?” which ranged from “very bad” (score of 1) to “very good” (score of 4). The regression was split according to the set BDI score ranges for minimally (N=2178), mildly (N=624), moderately (N=667), and severely (N=609) depressed individuals from the entire sample. Results Total SWLS scores were positively correlated with PSQI sleep quality score in minimally, mildly, moderately, and severely depressed groups (Rminimally=0.187, p< 0.001; Rmildly=0.129, p=0.001; Rmoderately=0.180, p< 0.001; Rseverely=0.438, p< 0.001). However, the R2 value was far larger in the severely depressed group than it was in all other groups R2adj/severely=0.191; versus R2adj/minimally=0.034, R2adj/mildly=0.015, and R2adj/moderately=0.031). This suggests that better sleep quality more strongly predicteds higher life satisfaction in severely depressed individuals, compared to those who were not severely depressed. Conclusion While poor sleep quality and lower life satisfaction both tend to be associated with more severe depression, these findings suggest the associations between sleep and life satisfaction are far stronger in those who are the most severely depressed. Consequently, these findings suggest that interventions that focus directly on improving sleep quality would likely be a fruitful approach to increase life satisfaction in severely depressed individuals. Support (if any)