Photo-acoustic stimulation: theoretical background and ten years of clinical experience

Light and sound effects have frequently been used for the induction of altered states of consciousness. Turning on and off light or sound leads to short-term excitation of the central nervous system, while longer lasting stimulation has led to drowsiness and mixed alpha-theta activity and to bodily relaxation with increased skin resistance, decreased EMG activity and a decreased salivary cortisol level; though an increased salivary IgA level and output of the salivary chaperone Hsp70 have also been reported. At the same time a strong trance inducing ability of photic stimulation (10 min) has been demonstrated. In open clinical studies orofacial psychosomatic patients have been treated: Atypical facial pain (n = 20) recovered in 34.9 %, improvement occurred in 40.4 %, with no effect in 24.7 %. Initial psychogenic denture intolerance (n = 9) symptoms recovered in 44.4 %, improvement occurred in 33.3 %, with no effect in 22.2 %. Chronic denture intolerance (n = 14) symptoms recovered in 21.4 %, improvement occurred in 50.0 %, with no effect in 28.6 %. In hyposalivation cases (n = 4), a significant increase of salivary flow rate and protein concentration occurred in 2/4. However, randomized controlled trials that might support the application of photo-acoustic stimulation are still lacking. Copyright © 2009 British Society of Experimental & Clinical Hypnosis. Published by John Wiley & Sons, Ltd.