Objective: Chronic pain patients have been reported to complain about poor sleep quality. Research aimed at delineating the predictors of poor sleep has produced conflicting results. Depressive mood and pain severity are the most frequently encountered predictors. This study aimed to find out whether chronic pain patients differed from healthy control subjects who had no pain on subjective sleep quality measures and, if so, which factors contributed most to poorer sleep quality.
Method: We compared 40 patients with chronic pain who met inclusion criteria with 40 healthy control subjects on the measures of sleep quality, anxiety, and depression. The predictors of sleep quality were investigated with multiple regression in the pain group.
Results: Chronic pain patients had higher scores than did healthy control subjects on the Beck Anxiety Scale, the Beck Depression Inventory (BDI), and the Pittsburgh Sleep Quality Index (PSQI). At the bivariate level, pain intensity, anxiety, and depression correlated significantly with poorer sleep quality. At the multivariate level, depression was found to be the only significant factor correlating with the quality of sleep, and the model explained 34% of the variance.
Conclusions: Chronic pain patients suffer from poor sleep quality--a function of depressed mood rather than pain intensity, duration, or anxiety. However, it is difficult to draw a causal relation in this relatively small sample size. Besides, our study sample comprised a mostly psychiatric population and may not represent the general group of patients with chronic pain.