FALLING ASLEEP PROCESS IN HUMAN LISTENING TO DIFFERENT TYPES OF MONOTONOUS SOUND: A PILOT STUDY
Development of non-invasive sleep-aid tools requires paying attention to techniques reducing and stabilizing fall-asleep time. Otherwise, all attempts to affect posterior sleep make no sense. The aim of current study was to compare effectiveness of listening through stereo earphones to three types of monotonous sound as one of those techniques. Namely, the sound engendering so-called "binaural beats" (BB), the sound containing ordinary ("monaural") beats (MB) and the sound containing pure tones without beats (imitation, IM) were applied. Methods. Data collected by polysomnographic record (EEG and eye movements) of falling asleep process of 14 subjects during listening to those three sound types then were analyzed to compare the fall-asleep time corresponding to each type. Results. The fall-asleep time during BB-stimulation was less than during IM in 10 subjects from 14; during MB-stimulation - in 5 subjects from 14. The fall-asleep time in BB-stimulation series was significantly (p < 0.05) less than in IM-series. MB-stimulation series contained no significant differences in fall-asleep time from IM-series. Conclusion. Binaural beat stimulation gives rise to the least fall-asleep time beside the sound containing ordinary (monaural) beats as well as monotonous beatless sound.