What part of the autonomic nervous system is activated during periods of rest and relaxation?

When you snuggle up to sleep at night, did you know that there is a part of your body that is hard at work? Yes, your parasympathetic nervous system is busy making sure you are ready to relax and get the most out of your rest. 

In fact, this system is always active, helping us to ‘keep calm and carry on’, especially after we’ve been stressed (such as running late for a meeting) or shocked (had a surprise birthday party thrown for us). So, what exactly is our parasympathetic nervous system, and why is it so important for our heart rate and sleep? Here’s your guide to helping your body keep its cool.

What is the parasympathetic nervous system?

The parasympathetic nervous system (PSNS) is part of your autonomic nervous system, which regulates your automatic body functions, such as heart rate, metabolism, and body temperature.

Your PSNS is all about slowing your body down, helping it to relax and rebalance, especially after anything stimulating has occurred. When you feel your heart rate begin to slow or the tension leaves your muscles after you’ve had a shock or been stressed, this is your PSNS in action.

Rest and digest vs. fight or flight

The parasympathetic nervous system works in balance with your sympathetic nervous system (SNS), with each one automatically helping your body adapt to our constantly changing environments.

Your parasympathetic nervous system takes over when your system feels it can return to ‘business as usual’, helping your various bodily functions find their usual rhythm again.

Your SNS takes over when we perceive that we are under threat (real or otherwise). It speeds up our heart rate, makes us tense and ready to spring into action. This is why your SNS is associated with our physiological ‘fight or flight’ response, which is triggered when we are stressed, frightened, or experience a situation of danger.

Your PSNS takes over when your system feels it can return to ‘business as usual’, helping your various bodily functions find their usual rhythm again. Our breathing slows and becomes deeper, and our digestive system becomes active again, among other functions. This is why your PSNS is often referred to as your ‘rest and digest’ response, in contrast to your SNS.

Parasympathetic effect on heart rate

Your SNS and PSNS work together to control your heart rate. When your body needs to increase your heart rate, your SNS releases catecholamine hormones (epinephrine and norepinephrine) to enable this acceleration. Then, when your body needs your heart rate to decrease, your PSNS releases the hormone acetylcholine to slow it down.

When we are stressed, excited, or have taken a stimulant such as caffeine, our heart rate will naturally rise. However, when we are constantly stressed or stimulating our bodies, we can frequently experience symptoms such as anxiety and heart palpitations. So, we mustn’t live our lives constantly running on adrenaline but instead find ways to relax and allow our PSNS to return our body to a state of everyday calm, known as homeostasis.

A great way to decrease the stress and anxiety in our lives is to activate our PSNS. We can achieve this through many different calming practices:

• Deep breathing: focus on taking breathes all the way down into your belly that expands your diaphragm as you inhale.
• Meditating: spend 10 minutes quieting your mind and focussing on your breathing.
• Touching your lips: this part of the body has many parasympathetic fibers running through them. By running your fingers across your lips, you will stimulate your PSNS.
• Trying a gentle movement practice such as yoga, qigong, or tai chi.
• Doing an inversion, such as a handstand or a headstand.
• Light stretching.
• Having a massage.
• Going for a walk in nature.
• Regular light to moderate aerobic exercise.

Parasympathetic nervous system and exercise

Obviously, when we exercise, we activate our SNS to raise our heart rate. So, how can regular exercise help our PSNS? 

Well, for starters, it is still hard at work when we’re active, even if our SNS is dominating. Your PSNS ensures that all the changes to your breathing, sweat production, and heart rate happen gradually. Otherwise, we’d find our bodily responses jumping about uncontrollably. 

Your parasympathetic nervous system ensures that all the changes to your breathing, sweat production, and heart rate happen gradually.

Our PSNS is also boosted by regular exercise because it produces endorphins. These happy hormones are great at helping us feel relaxed because they signal to the body that we aren’t in physical danger, enhancing our ability to relax back into homeostasis once we have stopped being momentarily stressed or excited.

Of course, your exercise plan should be all about balance. If you are only ever working out at a high intensity, you are constantly placing your body and nervous system under stress. Try to mix these sessions up with light to moderate-intensity exercise for at least 30 minutes on other days. 

Parasympathetic nervous system and sleep

As you can imagine, the ‘rest and digest’ division of our autonomic nervous system is essential for our capacity to get a good night’s sleep. Our SNS and PSNS are constantly active, but there are certain times when it is vital that one or the other dominates.

When it comes to sleep, ensuring our PSNS is activated is critical. We all know that trying to sleep when your body or mind feels stressed is much more difficult. If the events of our day have caused our SNS to dominate, your body will still be tense, and your mind will be racing. This will result in a poor night’s sleep, as our body struggles to relax and recover properly.

Nightly Recharge™ is a great way to measure how well your PSNS was able to take over your rest and recovery each evening. The feature looks at how the status of your autonomic nervous system and the amount and quality of your sleep compared to your usual night.

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Please note that the information provided in the Polar Blog articles cannot replace individual advice from health professionals. Please consult your physician before starting a new fitness program.

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Mar 2, 2020

What Is the Parasympathetic Nervous System?

The parasympathetic nervous system (PSNS), sometimes called the feed-and-breed or rest-and-digest system, is part of the autonomic nervous system, along with the sympathetic nervous system. Located between the brain and spinal cord, the PSNS is tasked with saving the body’s energy by slowing the heart rate and increasing the activity of the intestines and glands during periods of rest. It also relaxes the sphincter muscles in the gastrointestinal system.

Here are some of the body functions stimulated through the parasympathetic nervous system. The PSNS uses acetylcholine as its primary neurotransmitter, but other peptides may act on the PSNS as well.

• Sexual arousal
• Lacrimation (crying or shedding tears)
• Digestion: The PSNS dilates the blood vessels of the GI system to allow for greater blood flow.
• Salivation: The PSNS stimulates the salivary glands and speeds up peristalsis.
• Urination and defecation

The PSNS also constricts air passageways when the body needs less oxygen, such as during rest periods. It also constricts the pupils when closer vision is required. These functions complement those of the sympathetic nervous system, which is best known for stimulating the fight or flight response when the body perceives a threat.

When Is the Parasympathetic Nervous System Activated?

During times of stress, your body’s sympathetic nervous system activates your fight or flight response. It happens quickly so that the body is almost instantly ready to run or defend itself. In contrast, the parasympathetic nervous system’s job is to relax the body and use hormones to slow down those frantic responses once the threat is gone. The PSNS gives the body a calm and relaxed feeling over a period of time. The changes don’t happen as quickly as those of the sympathetic nervous system.

How Does Trauma Affect the Nervous System?

In periods of stress, the body’s fight or flight response activates. A normally regulated nervous system experiences the stress but returns to normal when the threat has passed. This period during which you have the ability to self regulate is called the window of tolerance, and most people move through several of these cycles daily. One example is rushing to get somewhere and running late but relaxing once you reach your destination on time. However, the system works very differently when the body experiences trauma.

Traumatic events push the nervous system outside its ability to regulate itself. For some, the system gets stuck in the “on” position, and the person is overstimulated and unable to calm. Anxiety, anger, restlessness, panic, and hyperactivity can all result when you stay in this ready-to-react mode. This physical state of hyperarousal is stressful for every system in the body. In other people, the nervous system is stuck in the “off” position, resulting in depression, disconnection, fatigue, and lethargy. People can alternate between these highs and lows.

In cases of extreme and chronic stress, such as ongoing trauma, complex PTSD may result. One example is children who are raised in abusive homes. Another is a soldier returning from combat. The nervous system becomes conditioned to exist in a state of fear. That state can continue into adulthood, triggered by things that would seem utterly unrelated to the childhood trauma. For example, the soldier may react to the backfiring of a car as if the sound is gunfire because he or she is in a constant state of fear, ready to react to the firing of a bullet.

How Do You Calm Down the Parasympathetic Nervous System?

A competent and trained therapist can help clients learn to activate the PSNS to control feelings of stress and anxiety, improve mood, boost the immune system, and reduce blood pressure. Many activities can help trigger this calming response in the body:

• Meditation and progressive relaxation
• Identifying and focusing on a word that you find peaceful or calming
• Exercise, yoga, tai chi, and similar activities
• Spending time in a serene natural place
• Deep breathing
• Playing with small children and pets

Other ways to activate the PSNS include getting a massage, repeating a calming chant or prayer, and participating in hobbies. Anything that you find calming, reassuring, and relaxing can be a way to wake up your parasympathetic nervous system.

Some of the techniques to activate the PSNS may come as a surprise. They focus on connecting your brain to the physical activity you are involved in, removing it from the “stuck” stage. Here are some examples:

• Gently touching your lips with two fingers can activate the PSNS because the lips are rich with parasympathetic fibers.
• Focusing on one thing at a time and avoiding the temptation to multitask can maximize the benefits of activating the PSNS.
• Visualization and imagery and picturing yourself in a peaceful place that you love can activate the calming actions of the PSNS.

Self Care and PTSD

Practicing self-care can help those who have PTSD learn to release stress and pull the nervous system back into regulation. These tips can help.

• Choose relationships that are safe. People who calm you and make you feel secure can help you activate your PSNS. People are social by nature and find comfort in connection with others. Isolation and superficial relationships can even aggravate mental health challenges.
• Take mindful breaths to connect your breathing to your conscious thoughts rather than to automatic panic responses.
• Connect with a trauma-focused therapist who understands these concepts and can help you recognize the signs of a dysregulated nervous system. A trained professional can help you identify what’s calming for you, and this may be different from person to person. For example, one person may find it soothing to sit still while others need the motion to feel at peace.

Does DBT Work for PTSD?

Dialectical Behavior Therapy (DBT) is a form of Cognitive Behavioral Therapy (CBT) intended to treat patients with the symptoms of Borderline Personality Disorder (BPD). However, since many of these patients also have Post-Traumatic Stress Disorder (PTSD) and vice versa, DBT can be useful in helping with both diagnoses. BPD and PTSD are both characterized by difficulty in controlling emotions, impulsive behaviors, and problems managing interpersonal relationships.

DBT was developed in the 1980s by Dr. Marsha Linehan. Like CBT, DBT emphasizes controlling thoughts and behaviors in a way that reduces symptoms. However, DBT also focuses on the acceptance of emotions and thoughts through the use of mindfulness skills. Researchers in a German study found that treating people with PTSD using DBT reduced the symptoms, such as depression and anxiety, and led to improvement that continued weeks after the therapy ended. Research continues into this promising use of DBT.

Contact MHS for Help Today

MHS offers DBT for adults and adolescents as young as 12, including those with co-occurring disorders, to help them reduce symptoms and improve quality of life. The Adherent DBT program at the Woodbury, Edina, Plymouth, and Roseville locations is closely modeled after the curriculum developed by Dr. Marsha Linehan. It is nationally accredited and certified by the Minnesota Mental Health Division Department of Human Services.

At MHS, DBT combines different techniques such as mindfulness, emotional regulations, interpersonal skills, and distress tolerance to effect lasting change. Clients identify personal goals, and MHS provides support to help them reach those targets. Therapists help clients get motivated and practice what they learn in therapy.

To learn more about how this intensive outpatient approach can help you, contact us today.

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Image Credit: Getty/vadimguzhva