Mindfulness meditation brings back focus on the present moment to attain a peaceful state of mind. A popular technique for this is to simply pay attention to breathing, “not because there is anything special about it,” explained minful.org, “but because the physical sensation of breathing is always there and you can use it as an anchor to the present moment.”
What does science have to say about mindfulness and breathing? The answer may lie in what slow breathing does to the heart rate variability (HRV), which reflects the cardiac vagal tone that has neural connections to the brain.
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Heart rate variability (HRV) and self-control
“Heart rate variability (HRV) has been suggested as a biological correlate of self-control,” researchers said. HRV is simply the time variations between heartbeats. We want a high resting HRV as it excites the cardiac (heart) vagal nerves that communicate with the brain. High resting HRV is said to enhance brain activities involved in the self-control of thoughts, behaviors, attention, or emotions.
“The neurovisceral integration model posits that cardiac vagal tone, indexed by heart rate variability (HRV), can indicate the functional integrity of the neural networks implicated in emotion–cognition interactions,” explained a 2014 review of Julian F. Thayer, a distinguished emeritus professor of psychological science at the Ohio State University. The review then outlined evidence that:
- Higher resting HRV is linked to “more effective emotion regulation.”
- Lower resting HRV is linked to “hyper-vigilant and maladaptive cognitive responses to emotional stimuli.”
The view still holds today. A 2020 review of Giampaolo Perna, MD, professor of psychiatry, and colleagues suggested that: “Vagally mediated HRV may serve as a global index of an individual’s flexibility and adaptability to stressors.” Put it another way, HRV indicates how efficient one controls their emotions or behaviors in response to stress.
High resting HRV is said to enhance brain activities involved in the self-control of thoughts, behaviors, attention, or emotions.
What difference will it make?
Many meta-analyses have investigated the effect size of resting HRV on various aspects of emotional and behavioral self-control. And all of them do find small-to-moderate effect sizes that are statistically significant.
(Note: r denotes Pearson’s correlation coefficient, with 0.10 indicating a small effect, 0.30 medium, and 0.50 large. Both d and g denote the difference between means, with 0.20 indicating a small effect, 0.50 medium, 0.80 large.)
These numbers suggest that resting HRV has more implications in disorders of impulse control, such as bulimia or alcohol dependence. In otherwise healthy people, resting HRV makes little difference in emotional or behavioral self-control. However, sometimes any bit of difference helps. On that note, what factors increase the resting HRV?
What Influences HRV?
People with healthy lifestyle behaviors — such as diet, sleep, and exercise — generally have high resting HRV. As follows, HRV also plays a role in lifestyle diseases, especially type 2 diabetes and cardiovascular diseases.
But a quicker and potent modulator of HRV is breathing. One session of 2–10 minutes of slow breathing (4–10 breaths/minute) can increase HRV compared to normal breathing (10–20 breaths/minute). This statement is based on at least ten studies cited in a 2017 review of Marc S. Russo, MD, director of Hunter Pain Clinic in Australia, and co-workers.
“Various studies have found that slow breathing increases amplitudes of blood pressure oscillations and HRV and that this is particularly significant at a respiration rate of 6 breaths per min,” the 2017 review emphasized. So, six breaths per minute for just 2–10 minutes can increase HRV and self-control of one’s psyche and behavior.
The effects of breathing on HRV is promptly evident at less than 10 minutes compared to lifestyle habits such as exercise, diet, or sleep. The reason is that HRV partly depends on the heart rate. And slow breathing slows the heart rate, which allows more time for variation between heartbeats.
Six breaths per minute for just 2–10 minutes can increase HRV and self-control of one’s psyche and behavior.
Lastly, a 2018 review of Angelo Gemignani, MD, professor of neuroscience, and associates refined on this topic. “We found reliable associations between the increase of HRV power…induced by slow breathing techniques at six breaths/min, and positive psychological or behavioral effects,” the authors concluded, which are “increased comfort, relaxation, pleasantness, vigor, and alertness, and reduced symptoms of arousal, anxiety, depression, anger, and confusion.” And all of these can also be thought of as some forms of self-control of one’s psyche and behavior.
One biological correlate of self-control is heart rate variability (HRV). HRV represents the cardiac vagal tone that is linked to emotion–cognition neural networks in the brain. Research shows that a higher resting HRV enables greater emotional regulation, and the opposite applies to lower resting HRV. Many meta-analyses have backed this up, showing statistically significant improvement in measures of emotional, attentional, and cognitive control, bulimia, alcohol dependence, compassion, and major depression following increased HRV. One fast way to improve HRV, studies show, is breathing at 6 breaths/min as it slows down the heart rate, which then allows more time for variability.