Combat Stress, Fatigue, and Anxiety with a Simple Trick: Drinking Icy Water and its Effect on the Vagus Nerve

Stress, fatigue, and anxiety can be alleviated with a seemingly simple hack - consuming a bit of icy water. The brief internal shock from the fluid has the power to stimulate the vagus nerve, leading to several improvements, including heart rate regulation. However, the activation of the vagus nerve isn't magical. It represents the application of knowledge about our body's physiological mechanism and the function of the vagus nerve.

The vagus nerve is the longest of the cranial nerves originating in the brain and extending to the abdomen. Along its path, it passes through the heart, lungs, and even some digestive organs. When active and "toned," it helps the body perform several functions like swallowing, breathing, maintaining heart rate, digestion, regulating emotions, and pain control, as explained by Ilene Ruhoy, a neurologist at Mount Sinai South Nassau Hospital, United States for the website Woman’s World.

The secret to the vagus nerve's involvement in so many operations lies in its direct connection with the central nervous system (CNS). Indeed, it's this nerve that transmits sensory information about the state of these organs. It can practically gauge how full an individual's stomach is.

However, when the vagus nerve ceases to perform its functions, the communication between the brain and body suffers, leading to neurological consequences like exhaustion, brain fog, anxiety, and mood swings. The daily stresses also weaken the vagus nerve, as explained by Paul Spector, a psychiatrist and director of Pantheon Medicine.

On the other hand, inducing the body to moderate, controlled, and timely stress can mitigate the negative effects associated with the weakening of the vagus nerve. This is where drinking cold water comes into play, forcing the body to adapt positively to this stressor, thus normalizing and regulating the internal temperature. This mechanism is known as hormesis. In response to thermal stress, the vagus nerve becomes active, and concurrently, the cortisol levels, the stress hormone, decrease in the blood due to the activity commanded by the nervous system.

In a bid to find ways to lower the heart rate, researchers from National Yang-Ming University in Taiwan asked over 50 volunteers to drink 250 ml (a glass) of icy water. This simple measure was effective in reducing heart activity, and part of the explanation lies in the activation of the vagus nerve. Published in the Clinical Autonomic Research journal, the study reveals that the vagus nerve activity increased by 39% in people who drank a glass of icy water. The most likely hypothesis is that the cold water activates the nerve endings in the esophagus, thereby stimulating the nerve and, in turn, leading to a reduction in heart rate. This results in a feeling of greater calm and less stress.

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