Stress and sleep deprivation are caused by the imbalance of autonomic nervous system, especially in low activity of parasympathetic nervous system (PNS), which affect daily living and impact economics severely. Since the PNS restores and conserves body and in response to stimulations. Moreover, voluntary control of respiratory rhythm, known as respiratory regulation, is considered a type of external stimulation to the body. Therefore, we studied the efficacy of respiratory regulation on PNS using heart rate variability.
In this study, 27 subjects completed a 27-min respiratory regulation session that consisted of one of four breathing modes.
The results of this study highlighted a significant elevation of HFnu, an indicator of PNS activity, immediately after each breathing mode (p < 0.001). We also found that sympathetic nervous system and PNS are easily activated and inhibited, respectively, during Mode 2 (inhalation 3 s, exhalation 6 s) breathing mode. This made the LF/HF ratio, an indicator of autonomic nervous system tone, during Mode 2, i.e., (29.3, p < 0.05) the highest among the breathing modes, allowing PNS to quickly become predominant, causing the body to relax during the following resting session. HFnu during Rest C (0.32, p < 0.05) was significantly higher than that during Rest B (0.25, p < 0.05).
These results suggest that Mode 2 can be used as a breathing model for long-term improvements in PNS function. This could lead to health promotion associated with stress by enhancing PNS activity.