These findings come from researchers at Stanford University, who aimed to quantify the effects of different types of breathwork on mood and emotional state. For the study, they divided 100-plus participants into four groups, assigning each a different five-minute intervention to do daily for a month with video-based instructions: cyclic sighing (which emphasizes the exhale), cyclic hyperventilation (which emphasizes the inhale), box breathing (which involves equal-length inhales and exhales), or mindfulness meditation (which involves passive observation of breathing, with no active control).
While all the groups experienced daily improvement in positive affect and reduction in anxiety and negative affect, the cyclic sighing group demonstrated the biggest improvement in mood and drop in respiratory rate (which is linked with a calmer state of being).
According to one of the study’s authors, psychiatrist David Spiegel, MD, director of the Center on Stress and Health at Stanford School of Medicine, this was just what they anticipated. “We thought that a type of breathing that emphasizes exhalation [like cyclic sighing] would be more likely to be self-soothing by triggering the parasympathetic nervous system,” he says. That’s because exhalation is the phase of the breathing cycle linked with a slower heart rate: “When you inhale, you reduce blood return to the heart, which causes it to speed up in response; whereas, when you exhale, you increase blood return to the heart, the vagus nerve is stimulated, and the parasympathetic activity slows the heart rate down,” says Dr. Spiegel.
“When you exhale, you increase blood return to the heart, the vagus nerve is stimulated, and the parasympathetic activity slows the heart rate down.” —David Spiegel, MD, psychiatrist
Because cyclic sighing is essentially a form of breathing that doubles down on exhalation, it’s a hack for shifting into that calmer parasympathetic state, and with repetition over time, for achieving stress relief as a result. To get specific, the cyclic sighing that participants practiced involved inhaling briefly through the nose to partially fill the lungs, then completing that inhalation, and finally, exhaling through the mouth for twice as long as the inhale.
That last bit is the most important part for achieving the soothing effect: “Making the exhalation double the length of the inhalation is extremely powerful for finding a sense of peace and calm in one’s mind and body,” says Zee Clarke, a mindfulness and breathwork expert for people of color (who wasn’t involved in the study) and author of the forthcoming book Black People Breathe. Though the above science may be new, “this style of breathing reflects a basic principle of traditional pranayama,” says Clarke, referring to the yogic breathing that’s previously been shown to reduce perceived stress, as well as the heart-related parameters of it.
Why the breathwork practice of repeated sighing can be so powerful for stress relief
Though the researchers didn’t specifically study the reason why cyclic sighing for just five minutes a day is so effective for stress relief and mood regulation, Dr. Spiegel suspects it’s related to how this kind of breathwork uniquely ties together processes of the mind and the body.
“What’s very interesting about breathing is that it’s right at the crux of automatic versus mentally directed physiological control,” says Dr. Spiegel. “If you don’t think about breathing, you breathe, but you can also change it, and the fact that you can take control and experience yourself taking control over a normally automatic physiological process may extend your sense of control over both mind and body.” In other words, with cyclic sighing, you can actually feel yourself calming yourself down, as your long exhales begin to activate your parasympathetic nervous system.
This feeling of control over one’s mental state of being may also help explain why the cyclic sighers in the study actually benefited more from the exercise the more days they did it, experiencing cumulative improvements in mood in a way that none of the other groups did. “There’s this feedback loop, where you become better able to regulate your mood and how your body feels, which is then encouraging, reminding you again that it doesn’t have to take much effort to feel calm,” says Dr. Spiegel.
Over time, the more you practice breathwork, the better you’ll be at utilizing it when you need it the most, too, says Clarke. “It’s important to do breathing practices to proactively stimulate the parasympathetic, so that you have a strong foundation when challenging things happen.” That’s why she suggests adding five minutes of exhale-focused breathing like cyclic sighing to your morning routine (ideally as the very first thing you do, so you don’t forget it), or scheduling it in your calendar to ensure it remains a daily ritual. Whenever the calendar reminder pops up, resist the urge to delay, she says; instead, adopt the mantra, “Today, I choose me” and begin.