This study was conducted to evaluate the positive effect of notation 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, EGG, ECG and respiration) were made continuously. Randomness of orally generated sequences was measured by RIP scores based on the Polya-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 stale and light sleep induced by floating enhanced random generation.