Assessment in Healthy Volunteers of the Analgesic Effect Monitored by the NOL Index During Hypnotherapy Session

to evaluate, in healthy volunteers, the analgesic effect of medical hypnosis versus a state of calm watch during a thermal harmful stimulation and monitored by a quantitative, objective criterion and validated in the literature that is the NOL index .Monitoring the NOL index will allow us to assess the level of nocipception linked to standardized thermal stimulation between the two states: hypnotherapy versus calm watch state. Each subject of the study will be subject to the two conditions (hypnosis versus calm watch state) during which participant will be subjected to the same type of thermal stimulation with the same monitoring of the parameters under study. The choice, for each subject, to start with the hypnosis session versus the calm standby session will be decided by randomization according to the "cross-over" drawing of this study, and before session 1. Using the NOL index, the investigators want to check what is the real and objective impact of hypnosis on the pain induced by a standardized harmful stimulus. If the investigators find a significant difference in the variations of the NOL index after harmful stimulation between the two situations (hypnosis versus calm watch state) then the investigators can offer this monitoring in future studies, to follow the induced hypnotic trance in patients with local anesthesia during surgery associated with hypnosedation.