The Unhappy Triad: Pain, Sleep Complaints, and Internalizing Symptoms.

There is limited understanding of the etiology and temporal relations of chronic pain, sleep complaints, and depression/anxiety. Several models have been proposed by which sleep disruption represents a common mechanism for the comorbidity of these symptoms. The goals of this study were to 1) clarify the boundaries of these domains and to 2) examine the relations of these symptoms over time following exposure to stressful and potentially traumatic experiences during a combat deployment. We found support for three distinct domains of sleep complaints, internalizing symptoms, and physical complaints. We tested two competing models that have been proposed in the literature, controlling for negative and positive emotionality. Internalizing symptoms strongly mediated the relation between sleep complaints and pain (total effect = .15, direct effect = -.05). The study suggests that increases in sleep complaints immediately following deployment increase the risk of internalizing symptoms and pain several years after deployment.