Although
sleep deprivation is known to heighten
pain sensitivity, the mechanisms by which sleep modifies nociception are largely unknown. Few studies of sleep-
pain interactions have utilized quantitative sensory testing models that implicate specific underlying physiologic mechanisms. One possibility, which is beginning to receive attention, is that differences in sleep may alter the
analgesic effects of distraction. We utilized the heat-
capsaicin nociceptive model to examine whether self-reported habitual sleep duration is associated with distraction
analgesia, the degree of secondary
hyperalgesia and skin flare, markers implicating both central and peripheral processes that heighten
pain. Twenty-eight healthy participants completed three experimental sessions in a randomized within subjects design. In the
pain only condition,
pain was induced for approximately 70-min via application of heat and
capsaicin to the dorsum of the non-dominant hand. Verbal
pain ratings were obtained at regular intervals. In the distraction condition, identical procedures were followed, but during heat-
capsaicin pain, subjects played a series of video games. The third session involved assessing performance on the video games (no
capsaicin). Participants indicated their normal self-reported habitual sleep duration over the past month. Individuals who slept less than 6.5 h/night in the month prior to the study experienced significantly less behavioral
analgesia, increased skin flare and augmented secondary
hyperalgesia. These findings suggest that reduced sleep time is associated with diminished
analgesic benefits from distraction and/or individuals obtaining less sleep have a reduced ability to disengage from
pain-related sensations. The secondary
hyperalgesia finding may implicate central involvement, whereas enhanced skin flare response suggests that sleep duration may also impact peripheral inflammatory mechanisms.