From the Guidelines
Activating the parasympathetic nervous system (PNS) has a positive effect on the body, promoting "rest and digest" functions, slowing heart rate, and increasing intestinal and glandular activity, which can lead to improved digestion, reduced stress-related symptoms, and enhanced overall well-being. The PNS works through the release of acetylcholine, which binds to muscarinic receptors on target organs, and is primarily active during states of calm and relaxation, counterbalancing the sympathetic "fight or flight" response 1.
Key Effects of PNS Activation
- Slows heart rate and increases heart rate variability (HRV), which is associated with a lower risk of cardiovascular death 1
- Increases intestinal and glandular activity, promoting normal digestion and elimination
- Relaxes sphincter muscles and stimulates saliva production, increasing digestive secretions
- Facilitates sexual arousal and reduces blood pressure by dilating blood vessels
- Enhances parasympathetic activity, which can improve digestion and reduce stress-related symptoms 1
Clinical Implications
- Activation of the PNS can be beneficial for patients with heart failure, as it can reduce the risk of death and improve symptoms 1
- Relaxation techniques, such as yoga and meditation, can enhance parasympathetic activity and improve overall well-being 1
- The vagus nerve (cranial nerve X) plays a crucial role in the PNS, influencing many internal organs and promoting relaxation and calmness
Evidence-Based Recommendation
Based on the most recent and highest quality study, activating the PNS through relaxation techniques, such as yoga, can have a positive effect on HRV and reduce the risk of cardiovascular death 1. Therefore, incorporating relaxation techniques into daily life can be a beneficial way to enhance parasympathetic activity and improve overall health and well-being.
From the Research
Effects of Activating the Parasympathetic Nervous System (PNS)
- The parasympathetic nervous system (PNS) plays a crucial role in promoting self-maintenance 'rest and digest' processes, and its activation has various effects on the body 2.
- Activation of the PNS can lead to a decrease in heart rate, as it controls the beat-to-beat heart rate variability 3, 4.
- The PNS also regulates other functions such as lacrimation, salivation, pupil response to light, gastrointestinal motility, micturition, and erectile function 2.
- In patients with chronic heart failure, reduced cardiac parasympathetic activity has been observed, which is related to the severity of left ventricular dysfunction 3.
- A decrease in PNS activity can dominate autonomic stress responses, as seen in a study on a free-living seabird, where handling stress induced a large and long-lasting depression of PNS 'rest-and-digest' activity 4.
- The effects of activating the PNS can be beneficial in certain conditions, such as reducing stress and promoting relaxation, but its dysregulation can contribute to various diseases, including cardiovascular disease and heart failure 5, 6.