Slow Wave Activity Is Reliably Low in Sleepwalkers: Response to Pressman et al. Letter to the Editor

Abstract

W e thank the editor for the opportunity to respond to the letter by Pressman et al. 1 This is a critique of the article by Cartwright and Guilleminault 2 recently published in the Journal of Clinical Sleep Medicine. We address the salient points their letter raised: The aim of our article Was the method appropriate?We based the method for our study on the hypotheses proposed by Espa et al. 4 as the conditions necessary to precipitate an occurrence of a SWS parasomnia. "The occurrence of SWS parasomnia requires not only a SWS pressure increase but also SWS arousal enhancement." This is the push/pull model that Pressman argued was a theory that only Cartwright held in the debate he refers the reader to review. [5][6][7][8] He argued forcefully and repeatedly that SW only occurred with an increase of SWS and that this was the accepted wisdom. In fact the two variable model was stated earlier by Broughton et al. 9 in describing the Ken Parks case. "These typical polysomnographic features of sleepwalkers suggest the coexistence of both pressure for deep sleep (SWS) and of heightened arousal causing inability to sustain such sleep." This opposite pressure model was used in the Pilon et al. 10 study which succeeded in eliciting sleepwalking events in the laboratory by combining increasing pressure for SWS by a prior period of sleep deprivation and increasing arousals from sleep by delivering auditory tones during the recovery sleep. Neither of these manipulations was successful when applied singly. It was this opposite pressure model that we tested in the case study reported in our recent paper.The evidence presented in court supported both pressures were present in the defendant on the night of the event (he had a period of prior sleep deprivation and excessive caffeine intake during the day before the event). Thus the conditions for a SW event were present. Furthermore we pointed out that "the additional history of snoring and a mild breathing disorder validated in the PSG may be a contributing cause of his low SWA, high CAP rate and arousal into non-conscious acts when sleep deprived and over-caffeinated."Pressman et al. 1 raise the question whether a low SWA in the fi rst NREM cycle, measured after the fact (not months or years) but specifi cally in this case eight months after the incident, can be a reliable marker of a predisposition to SW. The authors of the critique point out that the studies showing high reliability within subjects of the profi le of the

Sleep-Related Violence and Sexual Behavior in Sleep: A Systematic Review of Medical-Legal Case Reports

“…10 In their rebuttal, Cartwright and Guilleminault claimed that several studies make "a low slow wave activity a strong candidate to be a manifestation of the genetic vulnerability to abnormal delta arousals and therefore likely to be a stable characteristic of sleep." 80 Finally, due to the complex nature of SRV and SBS, the opinion of a properly credentialed sleep expert 81,82 and a multidisciplinary approach are highly recommended in forensic cases. 16,20 Forensic sleep medicine is at an embryonic stage.…”