Sleep and obesity in euthymic bipolar I patients: is there an association?

Abstract

The present study examined sleep patterns and obesity in euthymic bipolar I patients and assessed whether or not both sleep disturbances and obesity should be considered genetic traits of bipolar disorder. Furthermore, we examined the relationship between sleep and obesity. Using actimetry for 14 consecutive days, the sleep patterns of a sample of 102 euthymic (i.e. inter-episode) bipolar I patients (BD), 70 non-affected siblings (NAS) and 77 healthy controls (HC) were examined. To determine the occurrence of obesity in this sample, body mass index (BMI) scores were obtained for each participant. Our results revealed that the sleep patterns of both BD patients and NAS did not differ from those of HC. We did find that the total sleep time of NAS was significantly shorter than the total sleep time of BD patients, but the average sleep durations of all the groups can be considered normal (7-8 hours per night). The current study’s results indicate that BD patients and NAS do not experience persistent sleep disturbances when compared to HC. This suggests that sleep disturbance is not a genetic trait of bipolar disorder. Furthermore, we found no differences between NAS and HC on BMI scores, which indicates that obesity is also not a genetic trait of bipolar disorder. Our results did reveal that BD patients showed significantly higher BMI scores than both NAS and HC. Finally, the current study was the first to examine a relationship between sleep and obesity in BD, NAS and HC. No associations were found between obesity and sleep in any of the groups, suggesting that sleep and obesity might not be related within euthymic bipolar I patients, their non-affected siblings and healthy controls. Our findings suggest that overweight and obesity are highly prevalent in BD patients, with 66.7% of the current sample being overweight or obese. As overweight and obesity are known to cause many adverse effects within this population, these findings highlight the need to incorporate weight monitoring and weight loss strategies in the treatment of bipolar patients.