Evaluation of sleep architecture in practitioners of Sudarshan Kriya yoga and Vipassana meditation*

Yoga is an ancient Indian science and way of life that has been described in the traditional texts as a systematic method of achieving the highest possible functional harmony between body and mind. Yogic practices are claimed to enhance the quality of sleep. Electrophysiological correlates associated with the higher states of consciousness have been reported in long-term practitioners of transcendental meditation during deep sleep states. The present study was carried out to assess sleep architecture in Sudarshan Kriya Yoga (SKY) and Vipassana meditators. This was to ascertain the differences, if any, in sleep architecture following yogic practices. Whole night polysomnographic recordings were carried out in 78 healthy male subjects belonging to control and yoga groups. The groups studied were aged between 20 and 30-years-old (younger) and 31 to 55-years-old (middleaged). The sleep architecture was comparable among the younger control and yoga groups. While slow wave sleep (non-REM (rapid eye movement) S3 and S4) had reduced to 3.7 percent in the middleaged control group, participants of the middle-aged yoga groups (both SKY and Vipassana) showed no such decline in slow wave sleep states, which was experienced by 11.76 and 12.76 percent, respectively, of the SKY and Vipassana groups. However, Vipassana practitioners showed a significant enhancement (P < 0.001) in their REM sleep state from that of the age-matched control subjects and also from their SKY counterparts. Yoga practices help to retain slow wave sleep and enhance the REM sleep state in the middle age; they appear to retain a younger biological age as far as sleep is concerned. Overall, the study demonstrates the possible beneficial role of yoga in sleep– wakefulness behavior.