Stabilizing Sleep–Wake Cycles and Social Functioning in Bipolar Disorders: Effect of Interpersonal and Social Rhythm Therapy

<b>Background</b>: Functional impairments associated with bipolar disorder have a significant impact on daily life, including work, social relationships, and independent living. Bipolar disorder is treated with many approaches, with pharmacotherapy being the first choice; however, cases of relapse and side effects have been reported. The literature suggests that psychosocial interventions are effective in improving treatment adherence, recognizing early warning signs, enhancing self-management skills, and fostering open communication. The effects of interpersonal and social rhythm therapy (IPSRT) on circadian rhythm stability and social functioning in people with bipolar disorder remain uncertain. Therefore, this study is needed. <b>Methods</b>: This quasi-experimental study was conducted in the psychiatric outpatient clinic of a university hospital. Participants were recruited using convenience sampling from the psychiatric outpatient clinic. Eligible participants were then randomly allocated to either the intervention or control group using a coin-flip method. The dose of the intervention averaged 75 min per session with a weekly frequency over 12 weeks. Outcome measures included the Interpersonal Problem Areas Rating Scale, the Social Rhythm Metric Scale-II-5, and the Multnomah Community Ability Scale. Data were collected at baseline (week 0), post-intervention (week 12), and at follow-up (12 weeks post-intervention), and analyzed using repeated-measures ANOVA. <b>Results</b>: Participants in the IPSRT group demonstrated significant improvements in social rhythm regularity (SRM-II-5: 2.9 ± 1.3 at baseline, 3.7 ± 1.2 post-intervention, and 4.0 ± 1.5 at three-month follow-up; F = 18.5, <i>p</i> < 0.05, η² = 0.37). A significant between-group difference favoring IPSRT emerged at three months (t = 3.01, <i>p</i> < 0.05, d = 0.76). Social functioning also improved significantly in the intervention group (MCAS: 55.5 ± 7.4 at baseline, 63.7 ± 7.1 post-intervention, and 62.3 ± 6.9 at follow-up; F = 29.4, <i>p</i> < 0.05, η² = 0.49). Between-group differences were significant immediately post-intervention (t = 4.10, <i>p</i> < 0.001, d = 1.05) and at three-month follow-up (t = 2.73, <i>p</i> = 0.008, d = 0.72). <b>Conclusions</b>: IPSRT produced sustained improvements in social rhythm stability and social functioning, demonstrating its clinical value in the management of bipolar disorder.