Sleep quality and depressive symptoms among Korean older adults.

Depression and sleep disturbance frequently co-occur in older adults; however, their association remains underexamined in the Korean population. This study investigated the relationship between sleep quality and depressive symptoms in community-dwelling Korean older adults. Data from 924 participants (aged 55-80 years) from the aging-cognition cohort were analyzed. Sleep quality was measured using the Pittsburgh sleep quality index (PSQI), and depressive symptoms were assessed using the 30-item geriatric depression scale (GDS). Multivariate regression, subgroup analysis, and network analyses were conducted to evaluate associations and explore phenotypic patterns. Poor sleep quality was significantly associated with higher depressive symptoms (β = 0.715, 95% CI 0.6-0.831, p < 0.001), independent of covariates (β = 0.632, 95% CI 0.521-0.743, p < 0.001). Compared with sleep duration (r = -0.17, p < 0.001), the PSQI (r = 0.34, p < 0.001) showed a stronger correlation with the GDS. The key contributing domains included daytime dysfunction (C7; r = 0.32, p < 0.001), sleep latency (C2; r = 0.29, p < 0.001), and subjective sleep quality (C1; r = 0.28, p < 0.001). This association between PSQI and GDS was stronger in older adults aged ≥ 65 years, women, and married individuals. Sleep quality, particularly daytime dysfunction (C7), is closely associated with depressive symptoms in Korean older adults. These findings emphasize the importance of assessing sleep disturbance as part of depression screening and management in late life.