OBJECTIVE: Major depressive disorder (MDD) is associated with more pain complaints and an altered pain perception. Studies regarding the longitudinal relationship between depressive symptoms and pain processing have rarely been performed and have produced inconsistent results. To clarify how short-term alleviation of depressive mood is linked to changes in pain processing, the effect of sleep deprivation (SD) on pain and somatosensory thresholds, pain complaints, and mood was investigated in MDD patients.
METHODS: Nineteen drug-free inpatients with Diagnostic and Statistical Manual of Mental Disorders, fourth edition, diagnosis of MDD were investigated for 3 weeks. All patients received cognitive-behavioral therapy and were randomized to obtain either additional SD therapy (six nights of total SD, separated by recovery sleep) or no SD therapy (control group). Heat/cold pain thresholds, warmth/cold thresholds, measures of current pain complaints, and mood were assessed the evening before and the morning after SD as well as before and after a normal night sleep in the control group. Long-term changes of depressive symptomatology were assessed by weekly mood ratings.
RESULTS: Both treatment groups improved markedly in mood over the 3-week treatment period. SD regularly induced a moderate but statistically nonsignificant overnight improvement of mood, which was abolished by recovery sleep. Compared with the control condition, SD significantly decreased heat pain thresholds and nearly significantly cold pain thresholds; SD significantly augmented pain complaints the next morning. No such effects were observed for somatosensory thresholds.
CONCLUSIONS: SD induced differential short-term effects on mood and pain, with the patients being less depressed but more pain vulnerable.
