Daytime sleepiness, sleep disturbance and functioning impairment in bipolar disorder

OBJECTIVE: To verify the prevalence and clinical impact of excessive daytime sleepiness (EDS) in outpatients with bipolar disorder. METHODS: Eighty-one outpatients with bipolar disorder and 79 healthy control subjects were recruited. Patients were required not to be acutely manic or depressed. We used the Epworth Sleepiness Scale, the Pittsburgh Sleep Quality Index and the Functioning Assessment Short Test to assess sleepiness, sleep problems and functioning, respectively. RESULTS: Patients had a higher prevalence of sleepiness (40%) than the control group (18%). Sleepiness and sleep disturbance had independent impacts on disability in the multivariable model. CONCLUSIONS: This study suggests that EDS is a relevant clinical dimension in patients with bipolar disorder. It is a frequent symptom that often overlaps with other sleep disturbances. This study also reveals that once present it has the potential to increase functional impairment.