Resonance breathing (coherent breathing) at 6 breaths a minute

What is resonance breathing?

Every time you breathe in, your heart speeds up slightly, and every time you breathe out, it slows down. This is normal and healthy, and it is called respiratory sinus arrhythmia. At about six breaths a minute, these swings line up with the reflex that controls blood pressure (the baroreflex), and they become as large as they get. Researchers call this the resonance frequency, and breathing at it the basis of heart rate variability biofeedback.

You don’t need equipment to do it. Breathing evenly at five to six breaths a minute gets most adults close to their resonance rate.

When should you use it?

As a daily practice of 10 to 20 minutes, for stress or blood pressure. It is also a gentle way to wind down before bed. There are no breath-holds, so it suits almost everyone.

What the research shows

Blood pressure. A meta-analysis of 17 studies found slow breathing lowered systolic blood pressure by an average of 5.6 mmHg and diastolic by 3.0 mmHg, with results that varied a lot between studies. That is a modest effect, roughly what cutting back on salt can do. An earlier review of a commercial breathing device (RESPeRATE) found a similar drop overall, but no clear effect once the five trials funded by or involving the maker were left out. We grade the evidence moderate: the effect is consistent in direction but the trials are small, short and hard to blind. See breathing exercises and blood pressure.

Heart rate variability. A review of 223 studies found that slow breathing raises vagally mediated heart rate variability during practice, straight after a session and after a course of sessions. This is one of the most consistent findings in breathing research. Whether a higher reading means better health in the long run is less certain; see heart rate variability.

Stress and anxiety. A meta-analysis of heart rate variability biofeedback, which trains people to breathe at their resonance rate, found a large reduction in self-reported stress and anxiety compared with control groups, though the authors called for better-controlled trials.

Common mistakes

• Breathing too deeply. Slow breaths should be normal-sized. Big, slow breaths can still make you light-headed.
• Going too slow too soon. If six a minute feels like a struggle, start at 4 in, 4 out (7.5 a minute) and slow down over a week or two.
• Holding at the top. Let each in-breath turn smoothly into the out-breath.

Make it easier or harder

• Easier: use the Faster setting, or practise for 5 minutes instead of 10.
• Harder: lengthen the out-breath slightly (for example 4 in, 6 out), which many people find even more relaxing, and build up to 20 minutes.