From the Guidelines
Deep, slow breathing exercises are the most effective way to promote parasympathetic nervous system activity, as they directly stimulate the vagus nerve. This is supported by the understanding that the parasympathetic system affects the overall variability of heart rate and is influenced by respiratory sinus arrhythmia, which is the fluctuation in heart rate that occurs with breathing 1. Regular practices such as meditation, mindfulness, yoga, tai chi, and gentle stretching also enhance parasympathetic activity by combining controlled breathing with relaxation techniques, reducing stress hormones, and promoting a calm mental state.
Adequate sleep is essential for parasympathetic function, as this system dominates during rest periods. Dietary factors that support parasympathetic activity include omega-3 fatty acids, magnesium-rich foods, and probiotics that support gut health, which is closely connected to the vagus nerve. Certain medications like cholinergic drugs can directly stimulate parasympathetic receptors, though these are typically used for specific medical conditions under physician guidance.
Massage therapy, acupuncture, and warm baths can trigger parasympathetic responses through physical relaxation, counteracting sympathetic dominance and promoting the "rest and digest" state that allows the body to recover, repair tissues, and maintain homeostasis. It's also important to note that high-intensity endurance training can be an evolving risk factor underlying atrial fibrillation in middle-aged Europeans without overt structural heart disease, which can be mediated by an elevated parasympathetic tone, as suggested by a study published in Nature Reviews Cardiology 1.
However, the most recent and highest quality study on the topic of promoting parasympathetic activity, published in 2011 in Diabetes/Metabolism Research and Reviews, highlights the importance of controlled breathing and relaxation techniques in enhancing parasympathetic function 1. Therefore, practicing deep, slow breathing exercises and engaging in regular relaxation techniques is the most effective way to promote parasympathetic nervous system activity.
From the FDA Drug Label
CLINICAL PHARMACOLOGY Clonidine stimulates alpha-adrenoreceptors in the brain stem. This action results in reduced sympathetic outflow from the central nervous system and in decreases in peripheral resistance, renal vascular resistance, heart rate, and blood pressure. The reduction of sympathetic outflow from the central nervous system can be associated with an increase in parasympathetic activity, as these two systems have an inverse relationship.
- Key points:
- Stimulation of alpha-adrenoreceptors in the brain stem
- Reduction of sympathetic outflow
- Potential increase in parasympathetic activity 2
From the Research
Factors Promoting Parasympathetic Activity
- Acetylcholinesterase inhibitors, such as pyridostigmine, can enhance parasympathetic tone by increasing cholinergic input to the heart 3, 4, 5, 6, 7
- Cholinergic stimulation with pyridostigmine has been shown to increase heart rate variability and baroreflex sensitivity in rats 6
- Pyridostigmine administration can prevent alterations in cardiovascular autonomic control and gastric motility in L-NAME-induced hypertensive rats 4
- The treatment with pyridostigmine can improve cardiocirculatory function in rats with chronic heart failure by increasing parasympathetic function 7
- Pyridostigmine can increase parasympathetic tone, as evidenced by increased heart rate recovery and cardiac parasympathetic tone in rats 3
- In sedentary adults, pyridostigmine can decrease resting heart rate and increase postexercise heart rate recovery, indicating an increase in parasympathetic activity 5