Abstract
Yoga Nidra (YN) naturally stimulates a hypnagogic state wherein an individual is physiologically asleep yet maintains a certain awareness to follow a guide's instructions. The aim of this study was to investigate the effects of this aware sleep state on recovery-stress balance in two elite karate athletes adopting an idiosyncratic and multimodal approach. One male and one female athlete underwent a YN intervention. Before intervention, after intervention and three weeks later, recovery-stress balance specific scales, perceived stress, cognitive and somatic anxiety, subjective and objective sleep quality, and individual alpha peak frequency (iAPF) values were assessed. Perceived quality of recovery was continuously monitored for three months including the period of the investigation. Feelings and arousal levels before and after each YN session were also examined. Our results showed a YN general positive effect; however, the intervention had higher sport specific effects in the male compared to the female athlete. On the other hand, in the female athlete, YN seems to have effects both from an emotional and physical point of view. We also noted the intertwined relationship among interoception, perceived stress and YN effects. Also, findings suggest that iAPF modulation reflected improved recovery skills or a better control of stressful situations, while the acute effects on arousal levels were expression of anxiety or energy reduction. Overall, YN improved both the perceived quality of recovery and sleep quality, shedding light on the importance of YN for recovery-stress balance enhancement in the sport context.