The short answer
If you only remember one thing: make your exhale longer than your inhale. Inhale for about 4 seconds, exhale slowly for about 6. Do that for a minute or two and most people feel a measurable drop in agitation.
This works because of how your nervous system is wired. Your heart speeds up slightly when you breathe in and slows down when you breathe out. By deliberately lengthening the out-breath, you spend more time in the branch of the autonomic nervous system responsible for calming — the parasympathetic, "rest and digest" side — largely through the vagus nerve.
Three techniques worth knowing
1. Extended exhale (4-6 breathing). The simplest and most reliable. In for four, out for six. No breath-holding, nothing to memorise. This is the one to reach for in a stressful moment.
2. The physiological sigh. Two inhales through the nose (a normal breath, then a short second sip to top off the lungs), followed by a long, slow exhale through the mouth. Even one or two of these can take the edge off a spike of stress. It's the pattern your body already does naturally when you sob or settle down after crying.
3. Cyclic sighing. The physiological sigh, repeated for about five minutes. In controlled research comparing breathwork styles, a few minutes of this daily improved mood and lowered resting breathing rate more than equivalent time spent in mindfulness meditation — a striking result for something so simple.
What breathing can and can't do
Slow breathing is a real, fast-acting lever on your physiology. It reliably reduces the bodily symptoms of anxiety — racing heart, shallow breath, the wired feeling — in the moment. What it isn't is a cure for an anxiety disorder. If anxiety is regularly interfering with your life, breathing techniques are a genuinely useful tool alongside professional support, not a replacement for it.
Why "just calm down" never works — but this does
Telling an anxious brain to relax is useless because the feeling isn't coming from your thoughts first; it's often coming from your body. Breathing works precisely because it goes the other way. You can't consciously slow your heart rate, but you can control your breath — and a slow, long exhale is a back door into the same calming machinery.