The Science of Breathing in the Sweet Spot
With a just a few long, slow breaths jagged feelings may begin to ease into low-key self-control. Impulsiveness, anger, reactivity, and worry (to name just a few examples) can smooth out as breathing exerts influence over the heart.
When we’re in a pinch, our heart rate responds, sending stress signals from the heart to the brain along the vagus nerve, a two-way communication channel between the heart and brain. Numerous brain centers are quickly involved and ultimately the prefrontal cortex (PFC), the crowning brain center of self-regulation, signals a response. If the heart-brain communication system is functioning well, the PFC may empower the calming parasympathetic nervous system to apply brakes to unfavorable responses to stress. This signal travels back down the vagus nerve to inform the heart that we – not stress - are in control. Heart rate, respiration rate, and numerous other physical parameters dial down. The heart may then send its signal of self-possession back up to the brain, which may adjust the brake and so on (1, 2).
This two-way communication pathway appears to regulate a network of systems integrated through PFC “oversight” (2). If this network is disrupted consequences for working memory, attention, self-control, and emotional reactivity may arise (2, 3, 4). Dysfunction in this stress response system is also associated with numerous mental health disorders, including anxiety disorders, depression, ADHD and alcoholism (5) as well as physical diseases such as cardiovascular disease (6).
Breathing in the sweet spot has emerged as one of the best ways to intervene in this network, producing results such as improvements in cardiac function, anxiety, depression, ADHD, and alcoholism (5).
Heart Rate Variability
Balance between the parasympathetic (calming) and sympathetic (activating) nervous systems is expressed as a match between what’s going on around us and how the brain and body respond. Flexibility and adaptability mark a stress response system that adjusts well to environmental changes.
One measure of this vital resilience is called heart rate variability (HRV). The heart is particularly responsive to physical and environmental requirements so that a healthy heart rate oscillates from moment to moment. Oscillation in the rate of heart beats indicates high HRV and a flexible ability to integrate responses in the brain and body. Low HRV, or less variability in heart rate, suggests reduced capacity for adapting to the environment and is associated with both mental and physical consequences. Thus HRV is likely a pertinent measure of heart-brain communication, serving to indicate the strength of vagus nerve influence (4, 7, 8) in response to events and elements in the surrounding context.
Neuroplasticity may be involved in the quality of this stress response. This possibility is supported by neuroimaging studies (which examine cerebral blood flow), that indicate PFC regions associated with threat and safety are linked with HRV (9). Gray matter volume in these PFC regions also appears to be associated with memory of fearful events and HRV (9, 10). When differences in volume are observed in a brain region, the mechanics of the change may involve neuroplasticity - the changeability of neural circuitry that depends on experience.
In addition, prolonged excitatory sympathetic nervous system response may be linked to a lack of PFC regulation. Mental health disorders that include lack of control over neural processes related to PFC functioning such as generalized anxiety disorder, panic disorder, posttraumatic stress disorder and schizophrenia may result (2).
These data on volume, the PFC and the quality of the stress response are strong indicators that robustness – or the lack thereof - in the heart-brain stress response system may relate to neuroplasticity. Resilience may be reflected in neural growth and enhanced volume in key brain regions associated with adaptation to the surrounding environment. Likewise, reduced adaptability may be reflected in a lack of plasticity and lower cerebral volume.
The good news in this apparent capability for plasticity in the workings of the stress response system is the potential to intervene.
One of the most direct ways to tone HRV and the heart-brain communication system is through breathing (4, 11, 12, 13, 14, 15, 17, 25, 26). Most of us regularly breathe at about 12 breaths per minute (19). But when we corral our breathing into a slower pace at about 4-6 breaths per minute, data suggest that we likely insert positive change into the stress response loop, enhancing our ability to meet challenges with self-control (21).
That a simple breath should have that much power can sound like a stretch to anyone who’s ever been unable to stop worrying, couldn’t snap out of negativity, lost their temper or fallen into lapses of attention. But a majority of experiments suggest that breathing in this sweet spot appears to be a shortcut to self-control.
Breathing in the sweet spot has been shown to be the best range for positively affecting HRV. Breathing rates significantly above or below this range appear to have less potency (21). Control of HRV through breathing appears to be a way to directly affect both physiological and behavioral self-regulation associated with improved memory performance, emotional reactivity and self-inhibition tasks (4,14, 15, 22, 25, 26, 27).
In several experiments, just five minutes of breathing in the sweet spot led to improvement in HRV, reduced blood pressure, decrease in heart rate, and flexibility in arteries (21, 23, 24).
Investigation of slow breathing also suggests that a prolonged exhale may particularly target the vagus nerve (23). When we inhale, heart rate increases to reflect an activating response of the sympathetic nervous system. On exhale, heart rate slows and lends itself to the calming influence of the parasympathetic nervous system (7). Variation in heart rate between inhalation and exhalation then suggests a measure of the inhibitory parasympathetic vagal influence over the heart (HRV). Prolonging the exhale may thus enhance the activity of the calming parasympathetic system.
Breathing with Ocean Waves
While the ocean waves in our videos break in this sweet spot range there’s a difference between them and the way the scientific studies on self-control were designed. In those studies participants were typically instructed to breathe at the exact same rate for a precise number of minutes (21). Often the rate of six breaths per minute is used in experiments because it seems to have a particular synchronizing effect on the nervous system.
But ocean waves don’t break at rates of precision and neither does everyone breathe at the exact same rate with every breath when breathing naturally. We could have edited the film to make the waves break at precise time intervals but there’s something pleasing in the irregularity of natural rhythms like waves breaking or people breathing. So the waves break at pretty much the range of sweet spot rates they broke at during filming.
There is a change we've made in the waves however. Ocean waves often roll toward shore in sets. Even on the wild morning that the waves were filmed, there were long pauses of relative calm between the sets of waves. Since continuous breathing in the sweet spot appears to produce the desirable effect on self-control, the film was edited to join the sets together so you could breathe with the waves in this optimal, continuous way.
If you’re interested in a precise personal breathing rate, there are a number of biofeedback mechanisms that provide instant feedback on your breathing rate and/or HRV, which helps keep you in exact time. Some of them even help you identify your best rate – which likely varies from person to person and from time to time. The instant feedback provided by biofeedback mechanisms also seems to have a positive effect on the results.