Enhancement of randomness by flotation rest (restricted environmental stimulation technique).

This study was conducted to evaluate the positive effect of flotation REST on the production of random sequences, employing both behavioral and physiological measures. The subjects were 7 student volunteers who spent a 40-min. session lying alone on a bed in an isolation box and two 40-min. sessions floating in a commercially produced tank. Polygraph recordings (EEG, EOG, ECG and respiration) were made continuously. Randomness of orally generated sequences was measured by RIP scores based on the Pólya-Eggenberger distribution in three test sessions, e.g., pre-, during, and post-REST period. Randomness increased in the floating condition, while those parameters decreased in the bed condition. Sleep-stage analysis and EEG spectral analysis showed that the flotation REST induced a more hypnagogic state and light sleep than did in-bed REST. It is speculated that the hypnagogic state and light sleep induced by floating enhanced random generation.