Effect of sleep deprivation on the electrophysiological signature of habituation to noxious laser stimuli

Background Sleep deprivation induces hyperalgesia. However, this pronociceptive effect is not reflected at the electrophysiological level, since sleep restricted subjects show amplitude reduction of Laser‐evoked Potentials ( LEP ). We aimed to explore the contribution of habituation to this paradoxical LEP amplitude decline. Methods We compared LEP 's of 12 healthy students (23.2 ± 1.1 years) after habitual sleep ( HS ) and a night of total sleep deprivation ( TSD ). Twelve repetitive laser stimulus blocks (each comprising twenty stimuli) were applied under three attention conditions (‘focusing’ – ‘neutral’ – ‘distraction’ condition). Stimulus blocks were split in part 1 (stimulus 1–10) and part 2 (stimulus 11–20). The contribution of habituation to the TSD ‐induced LEP amplitude decline was studied by calculating the percentage amplitude reduction of part 2 as compared to part 1. Individual sleepiness levels were correlated with (1) averaged LEP 's and (2) the degree of habituation. Results TSD induced hyperalgesia to laser stimuli ( p  < 0.001). In contrast, depending on the attention condition, the P2 amplitude of the N2P2‐complex was significantly reduced (‘focusing’: p  = 0.004; ‘neutral’: p  = 0.017; distraction: p  = 0.71). Habituation of the P2 amplitude to radiant heat was increased after TSD (‘focusing’: p  = 0.04; ‘neutral’: p  < 0.001; distraction: p  = 0.88). TSD had no significant effect on N1 amplitudes ( p  > 0.05). Individual sleepiness correlated negatively with averaged P2 amplitudes ( p  = 0.02), but not with the degree of habituation ( p  = 0.14). Conclusion TSD induces hyperalgesia and results in attention‐dependent enhanced habituation of the P2 component. Increased habituation may – to a substantial degree – explain the TSD ‐induced LEP ‐amplitude decline. For this article, a commentary is available at the Wiley Online Library.