Biological rhythms are independently associated with quality of life in bipolar disorder

BACKGROUND Evidence suggests that patients with bipolar disorder (BD) experience biological rhythm disturbances; however, no studies have examined the impact of this disruption on quality of life (QOL). The aim of this study is to investigate the influence of biological rhythm, depressive symptoms, sleep quality, and sleep medication use on QOL in BD. METHODS Eighty BD subjects (44 depressed and 36 euthymic) completed questionnaires assessing QOL (WHOQOL-BREF), biological rhythm disruption (BRIAN), depressive symptoms (MADRS), and sleep quality (PSQI). The impact of biological rhythm disturbance, depressive symptoms severity, sleep quality, and sleep medication use on QOL was determined with multiple regression analyses. RESULTS BRIAN (β = -0.31, t = -2.73, p < 0.01), MADRS (β = -0.30, t = -2.93, p < 0.01), and sleep medication use (β = -0.45, t = -2.55, p < 0.05) were significant predictors of QOL in this model (F 4, 75 = 20.28; p < 0.0001). The relationship of these factors with subdomains of QOL showed that poorer social QOL was associated with greater biological rhythm disturbance (β = -0.43, t = -3.66, p < 0.01) and sleep medication use (β = -0.49, t = -2.35, p < 0.01), providing support for the social rhythm theory of BD. Physical QOL was associated with depression (β = -0.30, t = -2.93, p < 0.01) and biological rhythm disruption (β = -0.31, t = -2.73, p < 0.01). Main limitations include the cross-sectional assessment and the lack of objective measures of biological rhythms in relation to QOL. CONCLUSIONS Disruption in biological rhythm is associated with poor QOL in BD, independent of sleep disturbance, sleep medication use, and severity of depression. Treatment strategies targeting regulation of biological rhythms, such as sleep/wake cycles, eating patterns, activities, and social rhythms, are likely to improve QOL in this population.