The interrelationship between sleep and depression: a secondary analysis of a randomized controlled trial on mind-body-spirit intervention.

Objectives: To conduct a secondary analysis of a randomized controlled trial (RCT) that aims to understand the mediating effects embedded in a mind-body-spirit intervention for sleep and mood disturbances.

Methods: 126 adults with mild to moderate depression and subjective sleep disturbance, defined as Center for Epidemiologic Studies Depression Scale (CESD) scores from 10 to 34 and Pittsburgh Sleep Quality Index (PSQI) score > 5, participated in a waitlist-controlled RCT of an integrative mind-body-spirit intervention (I-BMS). Holistic well-being scale (HWS), a measure of the state of affliction and equanimity in mind, body and spirit, was included as a possible mediator. Data was collected at baseline and three-month follow-up. Mediation analyses were adopted to examine the pathways leading to sleep and mood improvements.

Results: After adjustments of baseline severities, changes in depressive symptoms partially mediated the effect of I-BMS on nighttime symptoms of insomnia (95% CI: 0.12-0.96), while exerting a full mediating effect on daytime symptoms of insomnia (95% CI: 0.14-0.64). The effect of I-BMS on mood was mediated by daytime symptoms of insomnia and spiritual orientation, but not by nighttime symptoms of insomnia (95% CI: 0.93-4.62).

Conclusion: A bidirectional relationship was found between sleep disturbances and depressive symptoms following a mind-body-spirit intervention. The relationship between daytime symptoms and depressive symptoms was especially strong. Of the HWS variables, spiritual orientation was the only significant mediator of mood improvement following I-BMS. Our findings suggest that efforts to optimize the treatment of comorbid sleep disturbances and depression are needed, especially the treatment of daytime impairments along with sleep and mood disruptions.