Wim Hof style breathing: how it works, and the safety rules that matter most
The breathing popularised by Wim Hof is rounds of fast, deep breaths followed by holding your breath on an empty exhale. It is powerful and it is also the one breathing technique on this site that has a serious safety warning, so that comes first. NanoTimer is not affiliated with Wim Hof or his organisation; this is a plain description.
Read this first: never in or near water
This style of breathing can make you faint with almost no warning. The fast breathing lowers carbon dioxide so much that your brain's urge to breathe is delayed, and you can black out before it kicks in. In water, that is fatal: shallow-water blackout has drowned experienced swimmers, and the Wim Hof organisation's own first safety rule is never to practise in or near water, including a bath or a pool.
So: never in or near water, never while driving, never standing up. Sit or lie down. Fainting during the breath-hold is common enough that you should treat it as expected and set up so a faint cannot hurt you.
How the breathing goes
A round is roughly thirty to forty deep breaths, in fully and out without forcing, at a steady pace. Then you exhale and hold with empty lungs for as long as is comfortable, without straining. Then you take a deep breath in and hold it for around fifteen seconds before letting go. People usually do three or four rounds.
The retention is not a competition. "As long as is comfortable" means you stop at the first real urge, not at your limit. Because the hold has no fixed length, this is a technique to follow by feel, which is why there is no fixed countdown for it here.
What it does, and what is still unproven
The immediate effects are real and easy to feel: tingling, light-headedness, a rush of alertness, sometimes an emotional release. Those come from the drop in carbon dioxide, not from anything mysterious.
The bigger health claims are where the evidence thins out. There is some research suggesting the method can influence the stress response and inflammation in the short term, but it is early, often small, and frequently overstated online. It is fair to say people find it energising and that some effects are being studied. It is not fair to promise it strengthens your immune system or treats disease, so we will not.
Who should skip it
- Anyone pregnant.
- People with epilepsy, heart conditions, high blood pressure, or a history of fainting.
- Anyone who feels unwell doing it: light-headed is expected, but pain, chest tightness or a racing heart means stop.
- If you have a medical condition, ask a doctor before starting, rather than after.
Prefer something gentler?
If you want the calm without the intensity, coherent breathing and the physiological sigh are slow, safe, and have guided timers here.
Frequently asked questions
- Why can't I do this in the shower or bath?
- Because you can faint without warning, and fainting with your face near water drowns you. This is not a theoretical risk: it has killed experienced practitioners. Do it sitting or lying on dry ground, away from water, every time.
- Does NanoTimer have a Wim Hof timer?
- No, and deliberately. The app has a Breathe section for guided patterns, but the breath-hold in this method has no fixed length, so a countdown would be misleading. Follow the retention by feel, with the safety rules above.
- Is it actually good for you?
- The short-term effects are real and many people find it energising. The stronger health claims are not well established, so treat it as an intense breathing practice you might enjoy, not as medicine.