Do highly sensitive persons experience more nonordinary states of consciousness during sensory isolation?

Our aim was to investigate whether or not highly sensitive persons experienced more nonordinary/altered states of consciousness (ASC) during 45 minutes of sensory isolation in a flotation tank, than did less sensitive persons. Psychology students (N = 57) were allocated to 1 of 2 groups (high and low levels of sensitivity) depending on their score on the Highly Sensitive Person Scale. Prior to the flotation session participants completed questionnaires to assess their degree of depression, anxiety, optimism, absorption, and how often they had experienced a mystical state. After the flotation session we assessed degree of ASC. The main finding was that the highly sensitive individuals experienced significantly more ASC during flotation than did the individuals in the low sensitivity group. Further, the highly sensitive participants had significantly more absorption and anxiety, and had experienced mystical states more frequently prior to flotation, in comparison to individuals with low-level sensitivity.