What box breathing is
Box breathing uses four equal parts: inhale for 4 seconds, hold for 4, exhale for 4, hold for 4. One full cycle takes 16 seconds. That works out to 3.75 breaths a minute. For comparison, normal resting breathing for adults is about 12 to 20 breaths a minute [Russo et al. 2017].
The pattern is also called square breathing or 4-4-4-4 breathing. It is a slow-breathing practice with holds. It is widely taught in military and first-responder stress training. Mark Divine, a former Navy SEAL, popularised it.
Trials of box breathing specifically are few. The research below is about slow breathing in general, not about this exact pattern. Treat it as a starting point, not proof.
What the slow-breathing research supports
A 2018 systematic review of 15 studies in healthy people found slow breathing (under 10 breaths a minute) was associated with increased HRV and respiratory sinus arrhythmia, EEG changes (more alpha, less theta), and reports of increased comfort, relaxation, pleasantness, vigor and alertness and reduced arousal, anxiety, depression, anger and confusion [Zaccaro et al. 2018]. The review is of healthy subjects and the studies are small.
A 2020 meta-analysis of 58 randomized controlled studies of HRV biofeedback found a small to moderate effect in its favour, largest for anxiety, depression, anger and athletic or artistic performance and smallest for PTSD, sleep and quality of life, with each based on a small number of studies. The authors describe it as useful as a complementary approach and say further research is needed for particular uses [Lehrer et al. 2020].
A 2017 study at Brigham Young University compared three groups for 15 minutes: breathing at the individual resonance frequency, breathing one breath a minute faster, and sitting quietly. The resonance group reported higher positive mood than the other two, showed a higher LF/HF HRV ratio than the control group, and had lower systolic blood pressure during a stressful mental task afterwards [Steffen et al. 2017].
A 2017 review describes the physiology of slow breathing: at around six breaths a minute, breathing and the blood-pressure rhythm of the baroreflex line up, which is why heart-rate swings grow [Russo, Santarelli & O'Rourke 2017].
These are associations from small or moderate studies, not proof. Individual results vary.
In the 2023 Stanford study, box breathing was one of the arms. Cyclic sighing showed the larger mood improvement [Balban et al. 2023].
How to use the timer
The timer sits above this text. It paces each of the four parts in turn. Follow the visual cue and the count.
Breathe through your nose where possible. Keep the breath light and unforced. Over-breathing causes light-headedness. Sit or lie comfortably. Stop if you feel dizzy.
Holds can feel uncomfortable. Shorter holds (2 or 3 seconds) are a reasonable way to start. Build up over days.
Two minutes per rate is enough for the resonance test. Twenty minutes a day is the practice dose in Leah Lagos's program and in most HRV biofeedback studies [Lehrer et al. 2020].
If you want to find your personal resonance frequency, use the resonance test. If you prefer a pattern with a longer exhale, try the 4-7-8 timer. For a simple pacer without holds, see the breathing pacer.
Worked example: one cycle at 4-4-4-4
Here is one full cycle, step by step.
| Phase | Seconds | Running total |
|---|---|---|
| Inhale | 4 | 4 |
| Hold | 4 | 8 |
| Exhale | 4 | 12 |
| Hold | 4 | 16 |
One cycle is 16 seconds. In one minute you complete 3.75 cycles. That is 3.75 breaths a minute. For comparison, 4.5 breaths a minute is 13.3 seconds a breath (inhale 5.3 s, exhale 8 s). The resonance pages use a 40:60 inhale-to-exhale ratio, as Lehrer's manual and Lagos's book prescribe. Box breathing uses equal parts.
Who should check with a clinician first
Anyone who is pregnant, has a heart or lung condition, a history of fainting, panic disorder, or epilepsy, or is being treated for a mental health condition. Slow breathing can lower blood pressure and heart rate. People on medication for either should ask their clinician. Nothing on this site is medical advice, a diagnosis or a treatment.
This site is educational and not medical advice.
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