Take a deep breath. Right now. Go on, I'll wait here. How does that feel?
You can do this anywhere, anytime, and tends to help. One of the effects of stress is its constricts your breathing, making it faster, shallower, and higher in the chest. This stressed breathing-style makes you feel psychologically more stressed, and so it can begin a negative feedback loop that might lead to health problems. In a study of a 153 heart attack patients, researchers found that almost all of them were primarily shallow breathers or "chest breathers."
The authors of New Directions in Progressive Relaxation Training: A Guidebook for Helping Professionals say that shallow, rapid breathing stimulates the sympathetic nervous system — the part of your nervous system responsible for stress reactions. "People can predispose themselves to anxious and tense inner experience," write the authors, "by breathing in this way."
There is some evidence that people who suffer from panic attacks keep their carbon dioxide too low by shallow breathing, which keeps them in a state of semi-hyperventilation. Apparently panic-attack sufferers notice the symptoms of hyperventilation such as feeling dizzy or a pounding heart or feelings of suffocation, they think something terrible is happening, and it scares them, which of course makes their heart pound even more, making them breathe faster, etc. Taking a deep breath can often stop this cycle. And a deep breath can make anyone feel more relaxed.
Although we breathe automatically, without any conscious effort on our part, we can also voluntarily control the way we breathe, and when we do, we gain more voluntary control of our emotional experience.
The method is to take a deep breath, somewhat slowly, and let it out slowly. If you've got the time and inclination, do it a few times. This is one of the simplest things you can do to reduce your stress and feel better quickly.
Adam Khan is the author of Antivirus For Your Mind: How to Strengthen Your Persistence and Determination and Feel Good More Often and co-author with Klassy Evans of How to Change the Way You Look at Things (in Plain English). Follow his podcast, The Adam Bomb.