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The Effects of Mouth Breathing and the Role of Heart Rate Variability Training in Mitigating Its Impact

Updated: Feb 22

For centuries, there has been a spotlight on breath, this interest has been encapsulated in the language of many cultures. For example, the English word spirit comes from Latin’s Spiritus which means ‘a breath’. The Hebrew and Greek translations of spirit also derive their origin from the word breath. Whereas Chi is used in China as the word for ‘the air we breathe’, but also means universal and cosmic energy of life (Ki in Japan plays a similar role).

This interest in the power of breath sparked an array of recommendations for the best way to control it. Pranayama yoga was the first to develop a doctrine around breath control, believing that mastering this art increased longevity. In the 1920’s, German psychiatrist Johannes Heinrich Schultz developed autogenic training to evoke relaxation. A central part of this training focuses on slow and deep breathing, and it is widely practiced to attenuate symptoms of anxiety, mild-to-moderate depression, irritability and fatigue [1]. Today, research on breathing for pain management and panic disorders is rampant [2,3,4,5].

Improper breathing is associated with many health and psychological disorders. For example, while being anxious can result in fast and shallow breathing.

Incorrect respiration due to mouth breathing or health issues can conversely increase ones chances of developing anxiety and depressive disorders.
More than 60% of individuals with chronic obstructive pulmonary disease (COPD) are proposed to have depressive disorders, whereas as the prevalence of developing an anxiety disorder ranges between 10-55% [6,7].

Understanding Mouth Breathing and The Unhealthy Consequences

Most individuals breathe through their noses by default. However, some people are either born with the tendency to breathe with their mouth, or develop this trait later in life as a habit [8,9]. Signs of breathing through your mouth comprise dry mouth, bad breath, hoarseness, snoring, feeling tired/irritable when you wake up, and brain fog.

Mouth breathing can have negative effects on the brain due improper air humidification and filtering, which can usher the following effects [10, 11,12]:

  • Reduced oxygen levels: When air is breathed in through the mouth, it bypasses the nasal passages responsible for filtering and warming the air before it enters the lungs. This can decrease the level of oxygen in the blood and thereby impair brain function, reduce alertness and cognitive performance.

  • Increased carbon dioxide levels: Mouth breathing can also cause an increase in the level of carbon dioxide in the bloodstream, which again impairs brain function, decreases attention span, and triggers headaches.

  • Reduced quality of sleep: Mouth breathing can lead to snoring and sleep apnea, which can disrupt sleep and lead to daytime sleepiness, reduced concentration, and impaired cognitive performance.

  • Reduced attention and memory: As noted, chronic mouth breathing can reduce attention and memory function, as the brain is not receiving enough oxygen to function at its optimal level.

  • Oral and dental health: Mouth breathing can also lead to enlarged tonsils and adenoids, bruxism causing wear and fracture/erosion of the teeth, malocclusion, periodontal disease, caries and impacted teeth, and myofascial pain.

Overall, mouth breathing is deleterious to brain function, i.e., attention, memory, and general cognitive performance. Mouth breathing in children is of particular concern due to its long-term effects on dentofacial development, for example, abnormal dental and maxillofacial development [13]. It is important to address chronic mouth breathing through various interventions, such as nasal breathing exercises, e.g., via heart rate variability (HRV), to improve brain function and overall health.

Introduction to Heart Rate Variability

Heart rate variability training can have positive effects on the brain by improving autonomic nervous system regulation, reducing stress, and promoting relaxation. The autonomic nervous system regulates various bodily functions, including heart rate, blood pressure, and breathing, and is composed of two branches: the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). The SNS is responsible for the body's fight-or-flight response to stress, while the PNS promotes rest and relaxation.

HRV training focuses on increasing the balance and flexibility between the SNS and PNS, which can help regulate stress and promote relaxation. By practicing HRV training, individuals can learn to control their heart rate variability and improve their ability to regulate their emotional responses to stressors.

Studies have shown that HRV training can lead to improvements in cognitive function, including attention, working memory, and executive function [14,15,19]. HRV training has also been shown to improve mood, reduce symptoms of anxiety and depression, and improve quality of life in individuals with various neurological disorders [16,17,18].

HRV Training as a Remedy for Mouth Breathing:

Breathing exercises can be an effective way to prevent mouth breathing and encourage nasal breathing. By practicing these breathing exercises regularly, you can strengthen your nasal breathing muscles and train your body to breathe through your nose instead of your mouth. This can help prevent the negative effects of mouth breathing on your health and cognitive function.

Heart rate variability training is not specifically designed to stop mouth breathing, but it can have a positive effect on the autonomic nervous system, which can improve respiratory function and promote healthy breathing patterns. As HRV training involves practicing techniques that help regulate the balance between the SNS and PNS branches of the autonomic nervous system. When the parasympathetic branch is activated, it's relaxing and calming effects improve overall breathing function.

By practicing HRV training regularly, individuals can increase their heart rate variability, which is a measure of the variation in time between heartbeats.

Higher HRV is associated with better cardiovascular health and overall well-being [20].
Additionally, HRV training has been shown to improve respiratory function, including increasing respiratory rate variability and reducing respiratory distress [21, 22, 23].
HRV biofeedback has been shown to improve respiratory function and reduce symptoms of respiratory disorders such as asthma and chronic obstructive pulmonary disease [24].


While HRV training may not specifically target mouth breathing, it can help improve overall respiratory function and promote healthy breathing patterns. It is important to note that HRV training should be used in conjunction with other interventions, such as breathing exercises and lifestyle changes, to address chronic mouth breathing and its associated negative effects on health and cognitive function.

Biofeedback can also be used to help individuals become more aware of their breathing patterns and improve their ability to control their breathing. For example, respiratory biofeedback can be used to train individuals to breathe at a slower, more regular rate, and to maintain a consistent pattern of breathing. This can be beneficial for individuals who tend to breathe through their mouth, as it can help them shift to a more nasal breathing pattern. Additionally, HRV biofeedback can be used to regulate the autonomic nervous system and promote relaxation, which can help reduce stress and anxiety and improve breathing function.

This Article was written by Anna Jusek



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