Breathing techniques

Slow breathing at about 6 breaths a minute reliably raises HRV while you do it. Evidence that it improves sleep is small but promising; 4-7-8 and box breathing have even less.

• Evidence: Weak
• Low effort
• Free
• Works: tonight

Why it matters

Most people breathe 12 to 20 times a minute at rest. Slow-paced breathing means slowing that to about 6 breaths a minute, often linked to the idea of resonance breathing. At this pace, heart rate rises and falls in step with each breath, and heart rate variability (HRV) goes up [2].

A 2022 meta-analysis of 223 studies found that slow breathing increases the parts of HRV linked to the vagus nerve, the main “rest and digest” nerve. The rise showed up during the breathing session, right after a single session, and after programs lasting several sessions [1].

The hope is that this helps you fall asleep when you’re wound up at bedtime. The sleep evidence is thin.

How to do it

Slow (resonance) breathing: our first choice

1. Lie in bed or sit comfortably. Lights low.
2. Breathe in gently through your nose for about 4–5 seconds.
3. Breathe out slowly through slightly pursed lips for about 5–6 seconds. The out-breath should be a little longer than the in-breath [2].
4. That’s about 6 breaths a minute. A 30-day trial used 4.5 seconds in and 5.5 seconds out [2]; an insomnia study used 3 seconds in and 7 seconds out [2][3].
5. Keep it up for 15–20 minutes. The trials used 15 minutes [2] and 20 minutes [3] before sleep.
6. If counting keeps you awake, use a breathing pacer. The 30-day trial used a phone app [2]; keep the screen dim.

4-7-8 breathing

1. Breathe out fully through your mouth with a “whoosh”.
2. Close your lips and breathe in quietly through your nose for a count of 4.
3. Hold your breath for a count of 7.
4. Breathe out through your mouth with a “whoosh” for a count of 8.
5. Repeat. One study used 3 sets of 6 cycles, with a minute of normal breathing between sets [4].

Box breathing

1. Breathe in for a count of 4.
2. Hold for 4.
3. Breathe out for 4.
4. Hold for 4. All four phases are equal length [7].
5. Repeat for a few minutes.

If any breath hold makes you dizzy or anxious, shorten it or switch to slow breathing, which has no hold.

Common mistakes

• Forcing big, deep breaths. The goal is a slow pace, not huge breaths. If you feel lightheaded or tingly, breathe smaller.
• Expecting it to fix insomnia that’s lasted months. Long-term insomnia needs proper treatment, such as CBT-I; see sleep restriction and when to see a doctor.
• Judging it by one night. In the 30-day trial, people practised every evening [2].

Effect on your sleep score

• HRV during the session: goes up, consistently [1]. If your watch takes an HRV reading while you breathe slowly, it will look higher. That doesn’t mean your overnight HRV changed.
• Overnight HRV: in a trial of 64 healthy young adults, 15 minutes of slow breathing each evening for 30 days raised overnight vagal HRV compared with using social media. It was measured with a portable ECG with stick-on electrodes, not a consumer wearable [2]. We found no study measuring overnight HRV from Oura, WHOOP, Apple Watch or Garmin after breathing exercises.
• Time to fall asleep and wake-ups: in 14 people with self-reported insomnia, 20 minutes of slow breathing before bed shortened time to fall asleep, reduced wake-ups and time awake, and raised sleep efficiency, measured in a sleep lab [3]. The control was breathing at 12 breaths a minute [2].
• Deep sleep, REM, resting heart rate: not clearly measured in the studies we found.

How confident: high for HRV during the session; low for sleep metrics and overnight HRV.

Evidence

Rated Weak for sleep. The HRV effect during and right after slow breathing is well supported [1]. But only two small trials link slow breathing to better sleep. One had 14 people with insomnia [3], and the other had 64 healthy young adults, measured sleep by questionnaire, and compared breathing with social media rather than a relaxing control [2].

4-7-8: we found no trial of 4-7-8 breathing for sleep in healthy adults. In 34 university students, 10 minutes of 4-7-8 breathing changed mood in women but didn’t change HRV compared with normal breathing [5]. In 43 young adults, it raised one HRV measure in those who weren’t sleep-deprived [4]. In 48 people with tinnitus, 6 weeks of 4-7-8 breathing improved insomnia scores, but the control group got no exercise at all [6].

Box breathing: a 2026 review found 8 small trials. Box breathing helped short-term stress and anxiety in some, but effects on HRV were inconsistent, and the trials focused on stress, mood and heart measures rather than sleep [7].

General information for healthy adults, not medical advice. If you have a sleep problem that lasts, read when to see a doctor. Sources checked 4 October 2026. Spot a mistake? Tell us.