Impact of sleep on clinical outcomes in a cohort of patients with bipolar disorder

Background and Objectives

Sleep disturbances are part of the diagnostic criteria for bipolar disorder (BD). They are prodromal symptoms of the disorder and are present during relapse and euthymia. We aimed to identify the impact of sleep, as an endophenotype, on BD patients in terms of clinical features including suicidality, severity of the disorder, somatic comorbidities, and functionality.

Methods

This is a secondary analysis of a cross-sectional study including 291 outpatients during follow-up at four sites in Spain. The score on the sleep domain of the Hamilton Depression Rating Scale (HDRS_sleep) was used to evaluate current sleep disturbances. Other psychometric tests, such as the Young Mania Rating Scale or the Hamilton Anxiety Rating Scale, were used to assess clinical status. Sociodemographic and other clinical variables were collected. Statistical analysis was performed using IBM SPSS Statistics, Version 27.0. Non-parametric tests and multiple linear regression were used.

Results

Of the 291 patients included in the study, 64.3 % (n = 187) were women. Mean age was 47.86 (SD=12.693). The sample was segmented into two groups: euthymia and non-euthymia, and the analysis was carried out separately in each. We observed no differences in either of these groups in HDRS_sleep with regard to sex, age, metabolic syndrome, coffee intake, or smoking. After adjusting for covariates, anxiety and functionality were significantly related to sleep in the non-euthymia group.

Conclusions

Sleep disturbances are frequent in BD, even during euthymia. Its impact on functionality and anxiety levels highlights the importance of targeting sleep in clinical practice to improve the outcome of the disorder.