Selective REM Sleep Deprivation Improves Expectation-Related Placebo Analgesia

<p><b>Remembered pain A) intensity and B) unpleasantness measured in the morning at control and placebo sites for REMSDs and Controls.</b> Statistical analyses revealed a group effect for concurrent pain intensity and unpleasantness (REMSDs vs. Controls, p = 0.028 and 0.030), a stimulation site effect (control vs. placebo test sites: p < 0.001 and p < 0.001), and an interaction (p = 0.006 and 0.030). <b>Analysis of remembered pain intensity (C) and unpleasantness (D) between placebo and control sites</b> revealed a significant between-group difference (p = 0.002) for pain intensity, but not for unpleasantness (p = 0.070) (mean ± standard error of the mean). Subjective assessments of pain intensity and unpleasantness were obtained using visual analog scale (VAS, 0–100).