The current study aimed to examine the differences in sleep quality, illness severity, and functioning in remitted bipolar disorder patients who are using mood stabilizers and antipsychotics either as monotherapy or as combination/additional therapy.

A total of 113 remitted outpatients with Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) bipolar disorder were recruited. The patients were classified on the basis of their current treatment regimen: 44 patients were receiving a single mood stabilizer, 21 patients were receiving a single antipsychotic, and 48 patients were receiving a combination therapy of a single mood stabilizer and a single antipsychotic. The Pittsburgh Sleep Quality Index (PSQI), Global Assessment of Functioning (GAF), and Insomnia Severity Index (ISI) were applied.

The GAF score was significantly lower in the combination group compared with the other 2 groups. Scores on the PSQI and ISI did not differ between the 3 groups. More than half (66.4%) of all patients had poor sleep quality. Total score on the PSQI was significantly correlated with age, body mass index, and GAF. Insomnia Severity Index was significantly correlated with the duration of illness, total number of episodes, and GAF. Multiple linear regression analysis indicated that GAF (β = −0.114) and ISI (β = 0.661) were significantly associated with the PSQI total score.

Our findings suggest that implementing interventions to enhance functioning is crucial for improving sleep quality in remitted bipolar patients.