How many times per day do you sigh? Chances are, the number in your head is off by a factor of about 10, according to a new study.
People actually sigh about 12 times every hour, or once every five minutes, researchers found. But these audible exhalations don’t necessarily signal tiredness or exasperation. Rather, physiological sighs are vital tokeeping the lungs functioning properly, the scientists said.
“A human lung has as much surface area as a tennis court, and so that’s all folded inside your chest,” study co-author Jack Feldman, a professor of neurobiology at UCLA, told Live Science. “The way that nature did it is that there’s 500 million little air sacs called alveoli. And each alveolus is a little sphere, about 0.2 millimeters [0.008 inches] in diameter.”