Conditioned pain modulation is not decreased after partial sleep restriction

Background: Sleep problems have been identified as a risk factor for several chronic pain conditions. Reduced sleep has been related to increased pain perception and it has been hypothesized that reduced pain inhibition may explain this. The aim of this study was to determine if sleep restriction (SR) affects heat pain perception and conditioned pain modulation (CPM). Methods: In a paired cross‐over design with two conditions (2 nights habitual sleep (HS) vs. 2 nights 50% SR) CPM was tested in 22 healthy individuals (14 women, 8 men). The test stimulus (TS) was 2‐min contact heat stimulation (47 ± 1.3 °C) to the volar forearm. TS was delivered before and during a 7 °C cold pressor test (conditioning stimulus, CS) to the contralateral hand. Results: TS was perceived as more painful after SR compared to after HS (p < 0.001). A stronger inhibitory CPM was found after SR versus after HS (p < 0.001). Conclusions: The results indicate that SR leads to increased heat pain perception, but not reduced inhibitory CPM. This contradicts general assumptions on the relation between SR and the CPM effect.