Slow breathing: does 6 breaths a minute lower stress?

How do you do slow breathing at 6 breaths a minute?

The studies used many paces and lengths, so there is no proven "best dose". This is a common-sense version based on what they tried.

1. Sit comfortably with your back supported. Rest your hands in your lap.
2. Breathe in through your nose for about 5 seconds. Breathe out gently for about 5 seconds. That is 10 seconds a breath, or 6 breaths a minute.
3. Keep it smooth and quiet, never forced. If 5 and 5 feels hard, try 4 in and 6 out, one of the patterns studied.
4. Keep going for 5 minutes. If your mind wanders, return to counting.
5. Try it once a day for a week and see how you feel. A short session before a stressful moment is also a fine use.

If you get lightheaded, make your breaths smaller and shorter, or stop and breathe normally.

Does slow breathing lower stress?

A 2023 meta-analysis in Scientific Reports pooled randomized trials of breathwork (Fincham et al.). For self-reported stress, it covered 12 trials with 785 adults. Ten tested slow-paced breathing and two tested fast-paced breathing.

The results:

• Stress: a small to medium drop compared with control groups.
• Anxiety: a similar small to medium drop across 20 trials.
• Depression symptoms: a similar drop across 18 trials.
• More sessions or longer programs did not clearly mean bigger effects.

The honest "but": none of the 12 stress trials was rated low risk of bias. They relied on questionnaires, with no objective measures, and there was too little follow-up to know what lasts.

Does slow breathing raise HRV?

A 2018 review in Frontiers in Human Neuroscience looked at 15 small studies of healthy adults breathing fewer than 10 times a minute (Zaccaro et al.). Slow breathing generally raised HRV, and some studies reported more relaxation and less anxiety, though results were mixed. The most consistent HRV findings were at about 6 breaths a minute.

The limits matter here. None of the 15 studies was randomized with a control group, and HRV was often measured during the breathing, not afterwards. Also, breathing at 6 a minute can push up one HRV measure just because your breathing rhythm shows up in your heart signal. So a higher number on your watch mid-exercise does not on its own prove you are calmer.

Does HRV stay higher after weeks of practice?

This is where the popular claim goes further than the data. In the 28-day trial of five-minute daily exercises, HRV and resting heart rate did not change significantly in any group (Balban et al.). That trial used a mix of techniques, not 6 breaths a minute specifically. Still, it is a good reminder: the HRV rise seen in studies is mostly short-term.

Two other studies used HRV as the outcome:

• In 47 healthy college students, a pattern of 5.5 breaths a minute with equal in and out time gave the highest HRV measures of four patterns tested, and all four felt more relaxing than normal breathing. I could read the abstract only (Lin et al., 2014).
• In 95 undergraduates, 15 minutes of breathing at each person's own best pace raised one HRV measure compared with sitting quietly, and raised positive mood. Two other HRV measures did not differ. It was a single session (Steffen et al., 2017). We go deeper in resonance breathing: find your rate.

Does slow breathing "balance your nervous system"?

A common explanation is that slow breathing stimulates the vagus nerve and "shifts you into rest mode". The authors of a well-known 2018 theory paper describe their proposed mechanism as "proposed, not proven", with supporting evidence that is correlational (Gerritsen and Band). It is a reasonable idea, but it is still a theory.

The research in a nutshell

How strong is the evidence? Mixed to early. The short-term HRV rise and small stress benefit look consistent, but most studies are small and rely on self-report.