The effects of total and REM sleep deprivation on laser-evoked potential threshold and pain perception

Abstract

We investigated the effects of total and rapid eye movement (REM) sleep deprivation on the thermal nociceptive threshold and pain perception using the objective laser-evoked potential (LEP) and the subjective visual analogue scale (VAS). Twenty-eight male adult volunteers were assigned into Control (CTRL), Total (T-SD), and REM (REM-SD) Sleep Deprivation groups. The T-SD and REM-SD volunteers were totally or selectively deprived of sleep for 2 and 4 consecutive nights, respectively. Pain parameters were measured daily during the experimental period. Volunteers were stimulated on the back of the hand by blocks of 50 diode laser pulses. Intensities increased between successive blocks, ranging from nonnoxious to noxious levels, and the LEP threshold was identified based on the evoked-response onset. Both the LEP threshold and VAS ratings were significantly increased after the second night of T-SD. No significant variations were observed in the REM-SD group, suggesting a predominant role for slow wave sleep rather than selective REM-SD in pain perception. Also, for both sleep-deprived groups, the mean values of the LEP threshold and VAS ratings showed a gradual increase that was proportional to the SD deprivation time, followed by a decrease after 1 night of sleep restoration. These findings demonstrate a hyperalgesic modification to pain perception (as reflected by the augmented VAS) and a concomitant increase in the LEP threshold following T-SD, an apparently contradictory effect that can be explained by differences in the ways that attention affects these pain measurements.

Activation of C-fiber nociceptors by low-power diode laser

“…The few investigators that have previously employed the darkening procedure reported only Aδ responses after high-intensity stimulation in three subjects 5 or have not focused on laser-evoked potentials, but on subjective pain and thermal thresholds 21,31 . In a previous study we were also able to study Aδ responses using the same methodology except for a larger area of stimulation 7 . When comparing our data with other ULEP studies, one must be aware of the differences in the referred stimulus intensities.…”

“…To date, only a few investigators have focused on human LEP elicited by diode lasers, which have applied high-power intensities to obtain only Aδ responses 24,25 or have observed simultaneous Aδ-and C-fiber responses that were restricted to a single subject 26 . Previously we were able to record LEPs related to Aδ fibers using a low power diode laser after skin blackening 7 , In the present study, we investigated the feasibility of selectively activating C-fiber responses in healthy volunteers using a low-power diode laser applied to tiny areas of blackened skin.…”

“…These results have been associated with Aδ-fiber activity, with none of the responses at latencies related to signals ascending through C-fibers 5,6 . Responses mediated exclusively by C-fibers, an ultra-late LEP (ULEP) at a latency of about 1000 ms, can be elicited only by special methods that allow their selective activation, such as low-power heating of the skin below Aδ threshold 7,8 , pressure nerve block 9 or the stimulation of tiny skin surfaces 10 . It is not clear yet why concomitant activation of Aδ-and C-fibers does not allow the individualization of both late and ultra-late LEPs 6,11,12,13 , interestingly, depending on the intensity of stimulation, both responses can occasionally be observed 7 , also related to this issue is the recent suggestion that laser pulses may also occasionally, in special circumstances, lead to tactile sensations 14 .…”

Fibromyalgia: A Critical and Comprehensive Review

“…Conversely, extended sleep time was associated with decreased heat pain sensitivity in healthy subjects [550], which echoes the observation that recovery after sleep deprivation is associated with significant increases in thermal and pressure pain thresholds compared to baseline even in cases where pain tolerance was not affected by the sleep deprivation protocol [551,552]. Nonetheless, a significant effect of sleep deprivation on pressure pain or thermal pain thresholds is not a consistent finding [544,553]. These discrepancies are most likely attributable to the low sample size in most of these studies, the lack of controls groups particularly in earlier investigations, the different sleep disruption or deprivation protocols, and the different outcome measures used for the assessment of hyperalgesia.…”

A Clinician’s Perspective on Treating Patients Suffering from Insomnia and Pain

“…Deprivation of non-REM sleep has been shown to induce muscular aches and pains in previously pain free individuals (Moldofsky and Scarisbrick 1976). The inverse has also been found, good sleep produces analgesic effects for pain sufferers (Azevedo et al 2011). In one recent study, even one night of total sleep loss was shown to greatly increase sensitivity to pain (Schuh-Hofer et al 2013).…”