A 15-Minute Abdominal Breathing Exercise Promotes Nap in Undergraduates: Instrumental Study Findings

The study purpose: To validate by polysomnography (PSG) tools the efficacy of deep abdominal breathing (AB) as a technique improving daytime nap in healthy subjects. Materials and methods: 43 healthy subjects participated in the study, of whom 22 were included into intervention group and 21 into control group. In the intervention group, nap PSGs were recorded for 30 min after performing AB for 15 minutes. In the control group, similar PSGs were recorded after 15 min of wakefulness. To assess the nap quality, standard sleep characteristics (latency, etc.) were determined from the subjects’ hypnograms. In the intervention group total sleep time was significantly longer and activation index was significantly lower than in control group, while sleep latency did not differ significantly. In addition, the electroencephalogram (EEG) spectrum power ratio in alpha (8–13 Hz) and theta (4–8 Hz) frequency bands was analyzed. Linear regression model of alpha/theta power ratio time series was constructed within the framework of statistical analysis. It was concluded based on comparison of coefficients of this model along with the time domain sleep characteristics, that AB exercise preceding daytime nap activates physiological mechanisms accelerating fall–asleep process and making sleep more stable. This finding may be useful in the development of non-invasive approaches to insomnia treatment.