The original research on the Pittsburgh Sleep Quality Index (PSQI) involved people with a diagnosis of depression.1 In a recent study of 201 veterans in which the PSQI was used, researchers found that "greater depression predicted both more severe pain and more sleep impairment."2 Some researchers have considered the possibility that depression and sleep impairment are bidirectionally predictive. Motivala and colleagues studied community-dwelling older adults: 200 had never had a mental illness, 143 had a history of depression but were in remission, and 67 were currently depressed.3 Sleep quality was assessed using the PSQI, depression assessment was performed with the Beck Depression Inventory, and health function was measured with the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36). The researchers found that compared with controls, older adults with a history of depression had impaired sleep quality and lower health function; those with current depression scored lower still in both areas. The researchers also found that "poor sleep quality was independently associated with declines in health perception" in all three groups.

Carole A. Smyth, MSN, ANP-GNP, APRN, BC

REFERENCES