Often associated with feelings of exasperation, annoyance or ­relief, sighing is a ubiquitous act. Every mammal does it, from humans to rodents. But what’s the point of these sudden, deep breaths? And if you live with a heavy “sigh-er,” should you ignore it? Or is there a deeper message you need to listen to? We asked a neurobiologist and a psychologist to explain…

The neurobiologist — Jack L. Feldman, PhD

Ask average people how often they sigh, and they’ll say two, maybe three, times a day. But the truth is, humans tend to sigh every five minutes…or 12 times per hour. We sigh a lot! Since most people say that we sigh only a few times a day, I think it is clear that we don’t notice our sighs. I am sure if you listen closely to someone you’re chatting with, you may not notice any sound, but you may notice (if you are looking for it) the deep breath. 

Human lungs contain a branching system of airways, at the end of which are tiny, spherical air sacs called alveoli…400 to 500 million of them. These alveoli are in charge of gas exchange, passing oxygen from inhaled air into the blood and then helping to remove carbon dioxide from the blood via ­exhalation.

Alveoli are lined with a liquid substance called pulmonary surfactant that lubricates the inhalation-­exhalation process. During normal ­breathing, some alveoli collapse, sticking together like a wet balloon. Sighing involves a sort of double inhale—a normal inhale followed by a second, deeper one before exhaling—and it happens unconsciously. It brings in about twice the volume of an average breath and is nature’s way of ­reinflating those collapsed alveoli. Going too long without sighing actually can cause the lungs to fail. In fact, ventilators (machines that help people with respiratory failure breathe) include mechanical sighs every few minutes to ensure optimal lung functioning. Sighs often are referred to as “augmented breaths” for their ability to expand the lungs. 

But there may be more to sighing than just sustaining life. Research suggests that sighing also may relieve stress. When my colleagues and I injected bombesin, akin to a peptide normally produced by the brain during times of stress, into the brain stems of rats, the ­rodents went from sighing 25 times per hour to 500 times per hour. We know that humans sigh more when we are stressed, so it may be that neurons in those brain regions responsible for processing stress-related emotions trigger the act of sighing as a way of providing a sort of psychological reset. More research is needed, but it would make sense, considering that other types of slow, paced breathing can have a profound, calming effect on one’s emotional state. For example, deep breathing slows the fight-or-flight response and can increase activity in your parasympathetic nervous system (the one responsible for breathing and heart rate) to reduce stress.

Harness the “sighing effect”: In healthy individuals, the body and brain do an excellent job of maintaining regularly scheduled sighs. But you can replicate their stress-easing effects by proactively taking a few slow, deep breaths whenever you’re feeling nervous or anxious…or before a high-pressure moment such as delivering a speech or trying to sink a putt. Yes, you will feel calmer even though these aren’t actual sighs. Even better, start a meditative practice such as meditation or yoga that features slow, paced breathing. There’s also box breathing, which involves inhaling for four counts…holding your breath for four counts…exhaling for four counts…and holding your breath for another four counts. The type of practice you choose isn’t as important as whether you enjoy it and will stick with it. Work your way up to 15 minutes a day, and you’ll likely notice meaningful improvements in your stress level. 

The psychologist — Ramani Durvasula, PhD 

When done purposefully and audibly, sighs are a potent form of communication. They’re considered nonverbal vocalizations, like laughter and crying out, and their power lies in their ability to convey a range of emotions, from satisfaction to contentedness to exasperation to annoyance to irritated ­acceptance. Interestingly, sighing seems to mean the same thing regardless of culture or language. Even deaf individuals use sighs to express relief, per a 2017 Current Biology article on this breathtaking topic. 

Often impulsive, emotional sighs can show up during arguments, where they send the message, Here we go again, to the other person. If your spouse is being toxic, for instance, going on yet another rant, you might sigh out of frustration, resignation or just as a form of internal acknowledgment that this person isn’t going to change. For the sigher, it feels less taxing than conjuring up the actual words needed to convey those thoughts.

Keep your sighs on a leash: Nonverbal communication of all kinds, such as sighs, raised eyebrows and glares, needs to be monitored as carefully as verbal communication. We often use the sigh as a means of communicating sentiments that feel frustrating or scary. But taking that same moment to recognize that you can communicate respectfully, with mindfully chosen words, can mean the difference between escalating a tense situation or defusing it. Use the seconds before the sigh to realize that you have something that deserves to be said and make the decision to either say it…or say nothing at all and walk away…or ask for a moment to process things, instead.

When you’re close with a frequent sigher: It’s easy to make assumptions about another person’s motivations or intentions when you’re on the receiving end of a sigh. Calmly check in with him/her by asking whether everything is OK. Keep a soft tone when making this inquiry so it doesn’t feel accusatory. It might turn out that the sigh wasn’t directed at you at all but just the other person’s own cleansing breath. On the other hand, if the sighs seem to be his way of expressing negative emotion, take a moment before responding. This may help prevent a blowup by serving as a much needed pause to regroup. 

Ready for some positive news? Sighs also are used to express a feeling of satisfaction, such as during the first few minutes of a massage…or relief, perhaps when your doctor tells you the lump is benign. In the latter example, sighing also represents a moment of processing—you’re waiting for, or receiving, an important piece of information, and once you’ve received it, you experience a letting go of those emotions with a big, cathartic sigh.