The Science Behind Your Sigh of Relief

What research reveals about sighing and how you can harness your breath to feel good anytime

Photo: Justin Paget/Getty Images

If you breathed a sigh of relief when you saw the Associated Press call the presidential race for Joe Biden on November 7, 2020, you weren’t alone. Sighs of relief were heard around the world. The New York Times reported that “Biden Victory Brings Sighs of Relief Overseas,” while The Guardian published an op-ed entitled “Catastrophe has been averted. Let us all breathe a big, long sigh of relief.”

So, what exactly is a sigh of relief?

Augmented breaths, or sighs, are a neurobiological phenomenon with physiological, psychological, and pathological implications. In simple terms, sighs consist of a normal breath followed by a second breath before your exhale.

Sighs are far more common than you might think. In fact, people sigh an average of 12 times per hour. Sighing may be so habitual because of the important role it plays in the human body. A 2014 study in Progress in Brain Research describes the three key functions of sighs: First, by filling the lungs so completely, sighing supports healthy lungs and alveoli. Second, sighing regulates arousal states, from fear to relaxation, for instance, or from sleep to wakefulness. Third, sighs reset and regulate respiration.

In simple terms, sighs consist of a normal breath followed by a second breath before your exhale.

If sighs are so salutary, it may be tempting to try to up your average. However, there’s reason to believe that artificially increasing your sigh rate may not be so helpful. One study in Physiology & Behavior found that while a spontaneous sigh induced a feeling of relief, an instructed sigh did not have the same benefit. Moreover, research on panic disorders suggests that increased sighing could actually elevate anxiety and even cause panic attacks.

Fortunately, there is a respiratory alternative that offers many of the same benefits as a sigh of relief: deep breathing. While sighs consist of two inhales followed by one exhale, deep breathing is a more balanced proposition. A deep breath includes one inhale that fills the lungs and one exhale that empties them. Deep breathing like this can relieve physiological tension and reduce blood pressure.

While deep breathing can technically be fast or slow, there appears to be an ideal rate from a health perspective: 5.5 breaths per minute. This is what journalist James Nestor found while researching his book, Breath: The New Science of a Lost Art. In the book, released earlier this year, Nestor writes that “the most efficient breathing rhythm occurred when both the length of respirations and total breaths per minute were locked into a spooky symmetry: 5.5-second inhales followed by 5.5-second exhales, which works out almost exactly to 5.5 breaths a minute… The results were profound, even when practiced for just five to ten minutes a day.” Nestor goes on to describe how one 9/11 survivor suffering from “glass lung” achieved “significant improvement” after just a few months of a slow breathing practice.

Among the research supporting Nestor’s finding is a 2014 study in the International Journal of Psychophysiology, which found that “Breathing at a rate of 5.5 breaths per minute with equal inhalation-to-exhalation ratio increases heart rate variability.” And increased heart rate variability is a good thing. According to the Harvard Health blog, a higher heart rate variability indicates the nervous system is more balanced and the person is more relaxed.

Most breathing apps offer a setting to select breaths per minute to support you in hitting this goal. But there is also a low-tech, low-math alternative. In an interview, Nestor advised that people focus on “slow and low” breaths through the nose. When this simple approach is combined with the sighs that organically arise in moments of relief, your breath becomes a powerful tool to support body and mind.

Writer with a master’s degree in psychology. Helpful, science-backed writing about mental health, mindfulness, and motherhood.

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