Feeling stressed? Try this.

“A kiss is just a kiss, a sigh is just a sigh…” sings Dooley Wilson, in the film Casablanca. But, Dear Dooley, I beg to differ. There are sighs, and then there are sighs. If you watch closely, you will see young children and puppies do this particular kind of sigh in their sleep. It’s something we do automatically to catch our breath after crying, and when feeling claustrophobic. And most of us do a version of this every five to 10 minutes. It’s called the “physiological sigh”– simply two short inhales, followed by one long exhale.

Stanford University neurobiology professor, Dr Andrew Huberman, shows that this kind of sighing can have a very quick and profound impact on reducing our stress.

What is stress?

We’ve probably all heard about the fight-flight-freeze response – when something in our environment tells us we’re unsafe, adrenaline courses through our body, causing our heart rate to speed up, our breathing to restrict, our skin to sweat. Basically, the fight-flight-freeze, or sympathetic nervous system response, says “yes” to certain bodily functions and “no” to others, which makes us more efficient at doing something, anything, to get ourselves out of danger. The legs are quickly activated with increased blood flow, which is why they tremor, or feel restless. Our heart muscle is activated so blood is pumped to our limbs more easily. Other areas, like our salivary glands, are switched off, which is why we get a feeling of a dry mouth.

The stress response is very good at keeping us alive in the short-term. Unfortunately, it’s also a very generic response that is activated in so many non-life or death situations – sitting in traffic, knowing that we’ll be late; having a difficult conversation with a loved one; seeing the latest COVID case number alert on our phone.

We often try to calm ourselves down, telling ourselves everything will work out. But trying to control our mind with our mind can be quite difficult, especially when we’re already stressed. We do have a much quicker access point to affecting our physiological state, however: our breathing.

Physiological sigh

At this point, some of you are probably saying, “yeah great, breathing. How am I supposed to leave in the midpoint of an important work presentation to do ‘slow breathing’ at my desk?” Well, the physiological sigh allows you to de-stress with remarkable speed, in the moment. Try this: take a sharp inhale, followed by another, then take a long exhale. Do three of these and notice how you feel. If you are like participants in this area of research, you may feel relaxed, even sleepy. In fact, this can be used to help fall asleep at night. Dr Huberman’s research shows that it’s also the fastest and most practical way to de-stress.

So how does it work? Firstly, it slows the heart rate. When you inhale, your diaphragm moves down, causing the heart to expand. Due to the greater volume, the blood inside the heart flows at a slower rate. This sends a signal to the brain that blood is flowing too slowly, and the brain consequently sends a signal back to the heart to speed up. As a result, heart rate increases when we inhale, and slows down when we exhale. And so, having a long exhale slows our stressed-out, speeding heart. This, in turn, tells our brain that we’re safe, and the body enters the parasympathetic, calming response to recover from the stressful experience.

The double inhale opens the alveoli in our lungs. The lungs have 500 million tiny air sacs called alveoli, which is where oxygen enters and carbon dioxide leaves the bloodstream. When we’re stressed, individual sacs collapse, which compromises the ability of the lungs to exchange oxygen and carbon dioxide. Carbon dioxide increases in our bloodstream, contributing to our feelings of stress. The double inhale opens these sacs again, vastly improving the lungs’ efficiency and ridding the CO2 from the bloodstream.

While we cannot control the myriad stressors life throws our way, we can control our response to them, in turn improving our overall psychological state, with this long, drawn-out sigh.