The Parasympathetic Nervous System: Rest, Digest, and Relax

Can individuals support their parasympathetic nervous system to maintain a relaxed state and avoid excessive agitation, stress, anxiety, and dysregulation?

Parasympathetic Nervous System

The parasympathetic nervous system (PSNS) involves organs and cells that release neurotransmitters that help the body maintain essential functions like heart rate, breathing, digestion, relaxation, thinking, and sleep. It is part of the autonomic nervous system, which includes the nerves and neurotransmitters that control the body’s internal organs to maintain reliable function. The autonomic nervous system regulates a continual balance between the parasympathetic nervous system’s rest-and-digest functions and the sympathetic nervous system’s fight-or-flight responses.

Functions and Responses

The parasympathetic nervous system includes nerves and neurotransmitters (chemical messengers) distributed throughout the body and is often described as promoting the body’s rest-and-digest state. The body’s needs regulate the control and effects of the system. Certain medications and health issues can modify or alter the function of the autonomic nervous system, including sympathetic and parasympathetic areas. The parasympathetic and sympathetic nervous systems collaborate to control cells, tissues, and organs. The body requires constant functioning and adjustment of both systems. (McQuade J. D. et al., 2017) Functions include: (Valenti V. E. et al., 2024)

• Saliva secretion to break down food.
• Maintaining blood pressure, resting heart, and breathing rate.
• Producing enzymes in the stomach and intestines to break down food further and absorb nutrients.
• Kidney balancing of fluid and mineral levels by producing urine.
• Constricting pupils (making the dark circle in the eye smaller) to see details up close.
• Maintaining focus and concentration to think, remember, and make decisions.
• Releasing hormones to fall asleep and stay asleep.
• Providing consistent muscle stimulation to maintain endurance for muscle activity.

All functions are adjusted based on the body’s needs.

Activation

The parasympathetic response constantly works to keep the body active, engaged, and healthy and can be stimulated simply by relaxing and resting. Individuals can sometimes focus on promoting their body’s parasympathetic activity through stretching, slow movements, relaxing sounds or music, meditation, and similar activities. Individuals who frequently feel anxious or stressed and have difficulty relaxing could benefit from guidance from a therapist or coach on learning to engage the parasympathetic nervous system. (Goren O. et al., 2024) This can involve activities such as guided meditation or talk therapy, which can help individuals work through fears and anxieties.

Dysregulation

Some medical conditions are associated with dysregulation. Heart disease, respiratory disease, sleep disorders, mental health conditions, and behavioral conditions can be associated with overactive or underactive parasympathetic or sympathetic nervous system regulation. (Veerakumar A. et al., 2022) Various mental health and physical health disorders can involve symptom fluctuations that affect the autonomic nervous system. For example, anxiety disorders can cause periods of overeating as well as loss of appetite and episodic indigestion, nausea, and vomiting. Symptoms of dysregulation can include: (McQuade J. D. et al., 2017)

• Excessive sleepiness
• Insomnia
• Difficulty concentrating
• Confusion
• Anxiety – nervousness or agitation
• A feeling of a rapid heart rate
• Shortness of breath
• Dry mouth
• Throat tightness
• Indigestion
• Stomachaches
• Nausea
• Vomiting
• Cold hands and feet
• Sweating or clammy hands
• Sadness
• Depression
• Dizziness or feeling physically off-balance

Any of these symptoms can develop and resolve quickly. Most individuals experience symptoms or parasympathetic nervous system dysfunction when an unexpected stressful event occurs, and the response is considered normal in traumatic, shocking, sad, or high-stress circumstances. (Veerakumar A. et al., 2022)

Medications may induce parasympathetic overactivity or underactivity until the medicine is broken down and removed from the body. (Valenti V. E. et al., 2024)

Nerves

The system comprises nerves that release hormones and neurotransmitters and nerves that respond to the hormones and neurotransmitters. Parasympathetic activation and response include: (Valenti V. E. et al., 2024)

• The nerves that activate the parasympathetic nervous system run throughout the body, primarily in the brain, heart, lungs, stomach, and intestines.
• The brain, heart, lungs, stomach, intestines, muscles, liver, kidneys, reproductive organs, eyes, and mouth are among the areas of the body that respond to stimulation.

The vagus nerve, one of the cranial nerves, is closely associated with parasympathetic nervous system activity. It runs from the brainstem down into the throat, heart, lungs, and digestive system. (Valenti V. E. et al., 2024) Surgical, medical, and alternative interventions are used to regulate the activity of the parasympathetic nervous system and are targeted toward regulating and controlling the activity of the vagus nerve. (Hernández-Domínguez R. A. et al., 2024)

PSNS Support

Living with any parasympathetic nervous system dysfunction can be challenging. For individuals with heart or lung disease, healthcare providers will evaluate the medical condition and recommend surgery or medication to control symptoms and avoid complications. (Hernández-Domínguez R. A. et al., 2024) Individuals who are living with a mental health disorder or behavioral disorder that is associated with any dysregulation of the parasympathetic nervous system activity may benefit from a combination of behavioral interventions and medication to help control symptoms long term. (Goren O. et al., 2024)

Injury Medical Chiropractic and Functional Medicine Clinic

The spinal cord has multiple functions in restoring, rejuvenating, and strengthening the nervous system. Chiropractic care has a highly responsive therapeutic effect on the nervous system because of its focus on the spine. Spinal decompression, traction, soft tissue manipulation, and other treatments help regulate and restore the function of the nervous system. Chiropractic benefits:

• Reduce and/or eliminate pain.
• Improves the quality of sleep.
• Increases energy.
• Improves cognition and clarity.
• Reduces or eliminates headaches and migraines.
• Improves digestive function.
• Improves balance and coordination.
• Increases flexibility and mobility.
• Regulates respiration.
• Regulates lower heart rate.

At Injury Medical Chiropractic and Functional Medicine Clinic, our areas of practice include Chronic Pain, Personal Injury, Auto Accident Care, Work Injuries, Back Injury, Low Back Pain, Neck Pain, Migraine Headaches, Sports Injuries, Sciatica, Scoliosis, Complex Herniated Discs, Fibromyalgia, Chronic Pain, Complex Injuries, Stress Management, Wellness & Nutrition, Functional Medicine Treatments, and in-scope care protocols. We focus on what works for every patient to restore function. If other treatment is needed, individuals will be referred to a clinic or physician best suited to their injury, condition, or ailment.

Chiropractic Secrets Exposed

References

McQuade, J. D., Penzel, T. E., Silk, J. S., & Lee, K. H. (2017). Parasympathetic Nervous System Reactivity Moderates Associations Between Children’s Executive Functioning and Social and Academic Competence. Journal of abnormal child psychology, 45(7), 1355–1367. doi.org/10.1007/s10802-016-0246-5

Valenti, V. E., Vanderlei, L. C. M., & Godoy, M. F. (2024). Editorial: Understanding the role of the autonomic nervous system in health and disease. Frontiers in neuroscience, 18, 1446832. doi.org/10.3389/fnins.2024.1446832

Goren, O., Paz, A., Bar-Kalifa, E., Gilboa-Schectman, E., Wolff, M., & Atzil-Slonim, D. (2024). Clients’ and therapists’ parasympathetic interpersonal and intrapersonal regulation dynamics during psychotherapy for depression. Psychotherapy research : journal of the Society for Psychotherapy Research, 1–15. Advance online publication. doi.org/10.1080/10503307.2024.2378038

Veerakumar, A., Yung, A. R., Liu, Y., & Krasnow, M. A. (2022). Molecularly defined circuits for cardiovascular and cardiopulmonary control. Nature, 606(7915), 739–746. doi.org/10.1038/s41586-022-04760-8

Hernández-Domínguez, R. A., Herrera-Orozco, J. F., Salazar-Calderón, G. E., Chávez-Canales, M., Márquez, M. F., González-Álvarez, F., Totomoch-Serra, A., Reyes-Cruz, T., Lip, F., & Aceves-Buendía, J. J. (2024). Optogenetic modulation of cardiac autonomic nervous system. Autonomic neuroscience : basic & clinical, 255, 103199. doi.org/10.1016/j.autneu.2024.103199