Objectives: Insomnia and pain are frequent complaints during the course of a major depressive episode. We analyzed the association between insomnia and pain symptoms using subjective and objective sleep measures.
Methods: This is a prospective, naturalistic follow-up study in a university-based psychiatric unit. Ninety-one Chinese patients were enrolled during an acute episode of major depressive disorder (mean age=48years, 73 women); 82 of them were reassessed 3months later using the same assessment on sleep, pain, depressive, and anxiety symptoms. Clinician-rated insomnia symptoms were obtained using the insomnia items of the Hamilton Rating Scale for Depression. Subjective sleep disturbances were assessed using the Insomnia Severity Index (ISI). Detailed sleep pattern was acquired using sleep diary and actigraphy. Pain intensity was evaluated using a verbal rating scale, a visual analog scale, and a multidimensional pain scale.
Results: Cross-sectional analyses found that insomnia symptoms and quantitative sleep parameters were related to pain symptoms. The correlations between sleep and pain scores were more significant after 3months of pharmacotherapy as compared to baseline. After controlling for the severity of anxiety and depression, the ISI total score and actigraphy-derived wake after sleep onset and total sleep time remained significant in predicting pain.
Conclusion: This study supports specific role of subjective sleep disturbances and actigraphic measures in predicting pain symptoms in major depressive disorder. Further studies using a micro-longitudinal design are necessary to find out the causal relationship between sleep and pain in depressed patients.
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