How Stress Impacts the Vagus Nerve
Written by Jessica Maguire. Originally published by Nervous System School.
Stress takes a toll on our physiology and can change the way our nervous system functions. Allostatic load refers to the wear and tear that can accumulate in the mind-body system, following periods of chronic and traumatic stress. To alleviate some of the effects of stress, we need to increase vagal tone.
Stress causes a shift of your nervous system away from its baseline by releasing mobilizing energy. In the short term, this helps to protect you. A healthy vagus nerve will slow the heart back down following stress, specifically via the vagal brake. It’s a connection to the heart’s pacemaker that helps you recover fully from a demanding or challenging event. You have an inbuilt capacity to deal with stressors and to recover fully from them. This process is known as allostasis.
When adversity comes up too often or goes on for too long, the vagus nerve gets blocked from helping the body to recover fully from the stress activation. Allostasis may stop working properly, and this can lead to nervous system dysregulation. This impacts the brain, immune and hormonal systems and allostatic load may build in any of these systems.
A chronically low vagal tone means the brake is off all the time and this can be like living in an unending state of emergency.
The heart beats faster and works harder and this can explain why hypertension is often associated with burnout.
Stress responses shift blood away from the digestive system to muscles needed to fight or flee, and this can cause gut disorders long-term.
The immune system changes in ways that promote inflammation, and this can lead to chronic pain.
In addition to the brain, immune and endocrine systems, low vagal tone impacts the respiratory, cardiovascular, digestive, and musculoskeletal systems. It can impact memory, willpower, emotions, metabolism, sleep, and inflammation. It can give rise to allergies, asthma, skin conditions, chronic fatigue, fibromyalgia, high blood pressure, heart palpitations, depression, anxiety, gut disorders, IBS, and migraines.
Improving the functioning of the vagus nerve can improve many chronic health issues that are stress-related. It can help to get to the root cause of stress-related illnesses rather than treating the symptoms. Otherwise, symptoms can return again when you’re under chronic stress.
A healthy vagal brake will release the correct amount of activation for coping with a demand and then apply the brakes to slow the heartbeat and your physiology back down. When allostasis is working properly the immune and endocrine systems function optimally, and so does the brain. It also makes you adaptable and flexible under stress. When your nervous system learns to recover fully from stress activation, you become more resilient and regulated.
Just like you might use exercises to restore normal function and movement of the body following a physical injury, after a period of chronic or traumatic stress you may need to rebalance your nervous system and restore allostasis to healthy functioning. This helps to re-establish the priorities of the body to maintain equilibrium and decreases allostatic load.
Although you can’t always control what happens to you, you can use a range of resources to re-calibrate your nervous system so that it learns to recover fully from stress activation. You can tip the scales the other way by shifting the state of your nervous system to a regulated one, allowing your mind-body system to function optimally. The key to this is having a healthy functioning vagus nerve.