Evaluation of sleep quality in patients diagnosed with bipolar disorder and major depression during remission period

BACKGROUND Sleep disturbances and residual functional impairment are increasingly recognized as important determinants of outcome in mood disorders, even during remission. Persistent disruptions in sleep may reflect underlying pathophysiological mechanisms and contribute to impaired psychosocial recovery. By comparing remitted bipolar disorder (BD) and major depressive disorder (MDD) patients with healthy controls, the present study sought to clarify the extent of these disturbances and their correlates. AIM To evaluate differences in sleep quality, psychosocial functioning, and insomnia severity among remitted patients with BD and MDD, in comparison with healthy controls. A secondary aim was to examine the clinical and psychosocial factors influencing sleep quality within these groups. METHODS The study included 135 participants: 45 remitted BD patients, 45 remitted MDD patients, and 45 healthy controls. Sleep quality was assessed with the Pittsburgh Sleep Quality Index, psychosocial functioning with the global assessment of functioning, and insomnia severity with the Insomnia Severity Index. Sociodemographic and clinical characteristics were also recorded. Comparative analyses were conducted to evaluate differences between groups, and regression models were used to identify predictors of sleep quality. RESULTS Both BD and MDD groups demonstrated significantly poorer sleep quality and higher insomnia severity compared with healthy controls. Poor sleep quality was observed in 75.6% of BD patients and 57.8% of MDD patients. Group differences were most pronounced in Pittsburgh Sleep Quality Index subdomains including sleep latency, sleep duration, and habitual sleep efficiency. Regression analysis identified insomnia severity (β = 0.510) and functional capacity (β = -0.043) as significant correlates of sleep quality, indicating that greater insomnia severity and lower functioning were independently associated with poorer sleep. CONCLUSION The findings underscore that even during remission, BD and MDD are accompanied by substantial impairments in sleep quality and psychosocial functioning. These results highlight the importance of addressing residual symptoms, particularly insomnia and functional difficulties, in long-term management strategies. Interventions aimed at improving sleep and enhancing daily functioning should be considered essential components of treatment to promote recovery and quality of life in remitted patients.