The physiological sigh

Fun fact: The average person sighs approximately once every 5 minutes. That’s 12 sighs per hour and 192 hours per day (while you’re awake).

Why does this matter? Well, it’s actually imperative that you sigh. Breathing requires 500 million little air sacs in your lungs (called alveoli) to be open, since that’s where the exchange of oxygen and carbon dioxide takes place. But over time, these air sacs collapse, which, if left unchecked, would eventually impair lung function. By sighing, the alveoli are “popped” open and normal breathing continues.

The good news is that we don’t have to consciously think about sighing (unless we’re trying to attenuate the stress response, which we’ll get to in a moment). Breathing is an automatic behavior whose major control center is located within a cluster of neurons in the brain stem, called the pre-Bӧtzinger complex. Sighing, a particular pattern of breathing, is caused by a molecule (i.e. peptide) that sends a signal to the pre-Bӧtzinger complex, telling it to initiate two inhales and an exhale.

While those anatomical facts are interesting, it all happens automatically and doesn't have anything to do with emotional regulation. Here’s where it becomes more relevant for those of us interested in high performance. One of the barriers to peak performance is stress, so by managing stress, we have better control over our performance. How does stress manifest in the lungs? Well, it does so physiologically. Let’s go back to those alveoli. If your alveoli are collapsing, then the exchange mechanism between oxygen and carbon dioxide breaks down and your body isn’t able to expel carbon dioxide. I’d consider a build up of carbon dioxide pretty physiologically stressful. So, by consciously sighing and opening those collapsed alveoli, the body may relieve physiological stress acutely.

This reduction in physiological stress is important because there is likely a relationship between physiological stress and emotional stress, although the exact neuro-mechanism has yet to be determined. When we consider stress management, we can either approach it in a top-down manner (by controlling cognition, which can then trickle down to the body’s stress response) or with a bottom-up approach (by controlling the physiological response, which then affects mental state). The “physiological sigh” is an example of a bottom-up stress management technique that can be used acutely to reduce stress or anxiety.

To practice the physiological sigh, receive an inhale, but before you get to the top, take another inhale. Then, expel all your air with an exhale. That’s it! A double inhale followed by a long exhale. That’s a physiological sigh.

Rest assured that your body does this on its own plenty of times throughout the day to manage the exchange of oxygen and carbon dioxide. But, the next time you’re feeling stressed or anxious, practice a conscious physiological sigh and allow your body and mind to let go with the exhale.