Insomnia and depression are common problems for people with chronic pain, and previous research has found that each is correlated with measures of pain and disability. The goal of this study was to examine the combined impact of major depression and insomnia on individuals with chronic pain.
The participants were patients with chronic musculoskeletal pain who underwent evaluation at an interdisciplinary treatment center. On the basis of semistructured interviews, participants were classified in three groups depending on whether they: (1) met criteria for major depression with insomnia (n = 38); (2) had insomnia without major depression (n = 58); or (3) had neither insomnia nor major depression (n = 47). The groups were then compared on self-report measures that included the McGill Pain Questionnaire, the Beck Depression Inventory, and the Multidimensional Pain Inventory.
Participants with major depression and insomnia reported the most difficulty on measures of affective distress, life control, interference, and pain severity, although the insomniac patients without major depression also had elevated scores on some measures. In regression analyses, insomnia severity ratings did not contribute uniquely to the prediction of psychosocial problems when depression was controlled, but they did contribute to the prediction of pain severity.
These results suggest that patients with chronic pain and concurrent major depression and insomnia report the highest levels of pain-related impairment, but insomnia in the absence of major depression is also associated with increased pain and distress.