Childhood trauma and sleep-related daytime dysfunction in patients with bipolar II disorder: Is social support a factor?

Background: Sleep quality is an important predictor for prognosis of bipolar disorder (BD). Factors associated with sleep quality in BD such as childhood trauma experience merit investigation. Methods: We used the Pittsburgh Sleep Quality Index (PSQI), Childhood Trauma Questionnaire (CTQ), and Measurement of Support Functions (MSF) to access patients with BD-I (n = 31), and those with BD-II (n = 34). Results: We found that 71.4% of patients with BD-I and 90.9% of those with BD-II had poor sleep quality. Significantly higher CTQ physical abuse score and poor life quality were found among patients with BD-II (b = −0.008, Wald χ2 (1) = 5.024, p < 0.05). This effect remained robust (b = −0.012, Wald χ2 (1) = 8.150, p < 0.01) after controlling the use of drug (sedative, benzodiazepine, antipsychotic, and antidepressant). Moreover, the experience of childhood trauma was associated with poor sleep quality among patients with BD-II. A buffer effect of social support between physical abuse and daytime dysfunction, as measured by PSQI, was found in patients with BD-II, but not in those with BD-I. Conclusion: Social adversity and support were associated with sleep quality in patients with BD-II. This finding implied a stress-buffering model in patients with BD-II. But the underlying biological mechanism remains unclear.