Diaphragmatic breathing, also called belly breathing, means breathing slowly so that your belly rises and falls more than your chest. Slow breathing like this helps your body shift toward its “rest and digest” mode, and people who do it before bed often say they fall asleep more easily. It is free, safe for most people, and takes five minutes. The research is encouraging, but more modest than many articles claim.
In this article
The short answer
- Slow breathing increases heart rate variability, a sign that the calming side of the nervous system is more active.
- In a 2017 study, eight weeks of breathing training lowered cortisol and improved attention.
- A 2026 review found that people report better sleep after slow breathing before bed, but sleep-lab measurements have not yet confirmed it.
- A simple routine: in through your nose for 4 counts, out for 6 counts, for 5 minutes.
How breathing affects your nervous system
Your autonomic nervous system has two main sides. The sympathetic side prepares you for action: your heart speeds up and you become more alert. The parasympathetic side helps you rest: your heart slows and your body calms down. The vagus nerve is a main pathway of this calming side.
You cannot simply decide to relax, but breathing is one part of this system you can control. Slow breathing, especially with a long out-breath, is linked with more parasympathetic activity and higher heart rate variability. A 2018 review of slow-breathing studies (Zaccaro and colleagues, Frontiers in Human Neuroscience) found these effects consistently, along with feeling more relaxed and less anxious.
What the research shows
| Study | Who | What it found |
|---|---|---|
| Ma et al., Frontiers in Psychology, 2017 | 40 healthy adults, 20 training sessions over 8 weeks | The breathing group had lower cortisol after training and better sustained attention; the control group did not change |
| Zaccaro et al., Frontiers in Human Neuroscience, 2018 | Review of slow-breathing studies | Higher heart rate variability, more relaxation, less anxiety |
| Systematic review, Sleep Medicine Reviews, 2026 | 9 studies, 457 people | Self-reported sleep quality and duration improved after slow breathing before bed; objective sleep measures were inconclusive |
So breathing exercises are a reasonable thing to try, especially if stress or a racing mind keeps you awake. They are not a proven cure for insomnia, and the studies are mostly small.
How to do diaphragmatic breathing
- Lie on your back or sit comfortably. Put one hand on your chest and one on your belly.
- Breathe in slowly through your nose for about 4 counts. Let your belly rise; your chest should move only a little.
- Breathe out slowly for about 6 counts, through your nose or gently through your mouth. Feel your belly fall.
- Keep going for 5 minutes. That is roughly 6 breaths a minute.
- If the counts feel strained, use 3 in and 5 out. It should feel easy, not forced.
Try this tonight
Dim the lights 30 minutes before bed, put your phone away, then lie down and do 5 minutes of 4-in, 6-out belly breathing. If you wake in the night and your mind starts racing, do it again.
Common mistakes
- Breathing too fast or too deeply. This can make you dizzy. Slow down and take smaller breaths.
- Lifting your shoulders. If your shoulders rise, you are still mostly chest breathing.
- Trying once and giving up. Like any skill, it gets easier with daily practice.
- Trying to empty your mind. You do not need to. Just bring your attention back to the breath when it wanders.
Other breathing patterns
- 4-7-8 breathing, made popular by Dr. Andrew Weil: in for 4, hold for 7, out for 8. Some people find the holds relaxing; others find them uncomfortable.
- Box breathing: in for 4, hold for 4, out for 4, hold for 4. It is used in some military and first-responder training for staying calm under stress.
- Longer out-breath: in for 4, out for 8. Simple, and many people find it calming.
No pattern has been shown to be clearly better than the others for sleep. Pick the one that feels most comfortable.
When to see a doctor
If you have asthma, COPD, a heart condition or panic attacks, ask your doctor before doing breathing exercises with long holds. See a doctor if poor sleep lasts more than a few weeks, or if you snore loudly or stop breathing in your sleep. Breathing exercises do not treat sleep apnea.
Frequently Asked Questions
How long before I notice a difference?
Many people feel calmer during the first session. Whether it helps your sleep over time varies; give it two to three weeks of daily practice.
Does belly breathing lower cortisol?
In the 2017 study by Ma and colleagues, eight weeks of training lowered cortisol in healthy adults. That is one small study, so treat it as a promising sign rather than a guarantee.
Will this work if I have insomnia?
It can help you relax, but it is not a full treatment. For long-term insomnia, cognitive behavioral therapy for insomnia (CBT-I) is the recommended first treatment, and relaxation techniques are often part of it.
Should I breathe through my nose or mouth?
Breathing in through your nose is usually more comfortable and makes slow breathing easier. Breathing out through the nose or the mouth both work.
Can children do this?
Yes. Use shorter counts and a simple picture, such as filling a balloon in the belly.
Your next breath
Diaphragmatic breathing will not fix every sleep problem, but it is a quick, free way to calm your body before bed, with real if modest research behind it. Try five minutes tonight, and keep it up for a few weeks.
Sources
- Ma X, et al. The effect of diaphragmatic breathing on attention, negative affect and stress in healthy adults. Front Psychol, 2017.
- Zaccaro A, et al. How breath-control can change your life: a systematic review on psycho-physiological correlates of slow breathing. Front Hum Neurosci, 2018.
- Eide EM, et al. Slow breathing techniques before bedtime and the effects on sleep: a systematic review. Sleep Med Rev, 2026.
This article is general information, not medical advice. See our medical disclaimer.
[…] Do not drop the basics. A regular wake-up time, a dark bedroom and less caffeine will do more for most people. See our guide to calming breathing before bed. […]