This study focused on social support and social strain and their cross-sectional associations with instabilities in sleep and social rhythms in inter-episode bipolar disorder (BD). Thirty-eight adults diagnosed with inter-episode BD Type I or II and 38 healthy controls completed measures of social support and social strain. Instabilities in sleep and social rhythms in the BD group were assessed with 28 days of diary and actigraphy. Associations between social support, social strain, and mood symptoms in the BD group were also examined. The BD group reported lower social support and higher social strain than the control group. Additionally, social strain was positively correlated with manic symptoms in the BD group. Furthermore, there was a cross-sectional association between social support and more stable sleep on actigraphy in the BD group, although social support was not correlated with future sleep instability. These results indicate that inter-episode BD is associated with deficient social support and elevated social strain compared to controls. Social strain may be particularly important given its association with manic symptoms. The results also raise the possibility that sleep instability is related to poor social support in BD
