title: Effect of sleep deprivation on the electrophysiological signature of habituation to noxious laser stimuli.
abstract: BACKGROUND
  Sleep deprivation induces hyperalgesia. However, this pro-nociceptive 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).
  
  
  CONCLUSIONS
  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.
authors: Chair of Neurophysiology, Centre of Biomedicine and Medical Technology Mannheim, Heidelberg University, Mannheim, Germany.
authors: S
authors: S
authors: Schuh-Hofer
authors: Chair of Neurophysiology, Centre of Biomedicine and Medical Technology Mannheim, Heidelberg University, Mannheim, Germany.
authors: U
authors: U
authors: Baumgärtner
authors: Chair of Neurophysiology, Centre of Biomedicine and Medical Technology Mannheim, Heidelberg University, Mannheim, Germany.
authors: R-D
authors: RD
authors: Treede
mesh_terms: D000328:Adult; D001143:Arousal; D001288:Attention; D003071:Cognition; D004569:Electroencephalography; D005071:Evoked Potentials; D005260:Female; D006185:Habituation, Psychophysiologic; D006358:Hot Temperature; D006801:Humans; D006930:Hyperalgesia / Q000209:etiology / Q000523:psychology*; D007834:Lasers; D008297:Male; D010147:Pain Measurement; D058748:Pain Perception; D011597:Psychomotor Performance; D012892:Sleep Deprivation; D055815:Young Adult