Study experimental protocol. The study subject will entry the experiment room, and TENS, EEG and EMG electrodes will be placed and will be tested before starting the session. TENS and ANS polygraphs will be tested and setup for the experiment. Then, the patient will be placed on the medical bed with their eyes open to allow for room acclimation. After 10' of room acclimation, the ANS recording session will start. The first 3' will be dedicated to adaptation and software setup; then, ANS data will be recorded for 5' (basal). At this point, the test group (represented by red rectangles) will receive sensorial TENS, whereas the control group (represented by blue rectangles) will not. TENS stimulation will be administered for 40' in total, allowing 1' for adaptation and 39' of useful recording time (T1). The end of TENS stimulation will be followed by 1' of recovery. Finally, the effects of ULF-TENS will be recorded for 5' (recovery). At each phase (Basal, T1, Recovery) serum and saliva will be sampled using a glycemic stick technique and sterile tubes.