Breathing Exercises

What it is

Slow breathing means breathing at a slow, steady pace, often about six breaths a minute with long, relaxed breaths out [1][2]. Trials have tested several versions: diaphragmatic (belly) breathing [3], pursed-lip breathing combined with counting [4], bee-humming breathing [5], box breathing [6], and device-guided breathing, where a device sets the pace [7]. Studies ranged from a single 5-minute session [5] to 12 weeks of practice [8].

How it might work

The proposed mechanism is that slow breathing shifts the nervous system toward its calming, parasympathetic side, which shows up as higher heart rate variability [9]. In people with COPD, controlled breathing improved baroreceptor sensitivity, a measure of the reflex that adjusts blood pressure, in a review of 18 studies [10].

What the research says

Blood pressure. A 2019 meta-analysis of 17 randomized trials found that slow breathing reduced systolic blood pressure by 5.62 mmHg and diastolic by 2.97 mmHg, though results varied widely between trials [11]. A 2017 review of six trials in people with cardiovascular disease found that slow breathing lowered systolic pressure by 6.36 mmHg, diastolic by 6.39 mmHg and resting heart rate by 1.72 beats a minute [12]. In a 110-person trial of people admitted with hypertensive urgency, pursed-lip breathing with counting lowered systolic pressure 9.80 mmHg more than usual care after three hours [4]. In an 8-week trial of 32 older adults with isolated systolic hypertension, slow loaded breathing lowered home systolic pressure by 20 mmHg, against 5 mmHg with the control breathing [2].

Anxiety and stress. A 2026 review of 48 randomized trials of diaphragmatic breathing reported consistent benefits for anxiety, though most primary studies had weak methods [3]. In a 98-person single-blind trial of student paramedics, twice-daily slow breathing for 12 weeks lowered anxiety, stress and depression scores compared with controls, and the authors note differential dropout between the groups [13]. In 78 hospitalised psychiatric patients, resonant breathing reduced self-reported anxiety after 10 sessions [1]. In a trial of 66 people given a virtual stress test, box breathing and prolonged exhaling before the test blunted rises in heart rate, anxiety and an alpha-amylase marker of stress compared with normal breathing [6]. In a trial of 139 students, one session of slow breathing with a long exhale reduced stress compared with an active control [14].

Heart rate variability. A 2022 meta-analysis of 223 studies found that heart rate variability rose during slow breathing, after one session and after multi-session programmes [9]. In a 100-person trial of adults with high blood pressure, 4 weeks of slow breathing increased a heart-rate-variability measure and lowered blood pressure and salivary cortisol compared with controls [15].

Sleep. A 2026 review of nine studies (457 people) that practised slow breathing before bed found that self-reported sleep duration and quality improved, while objective measures of sleep were inconclusive [16]. In the psychiatric trial above, resonant breathing also reduced insomnia symptoms [1].

Mood. In the 139-student trial, mood improved in the breathing group and fell in the control group after one session [14]. The paramedic trial above also reported lower depression scores [13].

Doses used in studies

Trials used a set slow pace, at 10 breaths a minute or fewer [11], and at 6 breaths a minute in several studies [2][1]. One blood pressure trial used 30 minutes a day, 5 days a week, for 4 weeks (20 sessions) [15]. A heart-failure trial used 30 minutes a day of device-guided breathing for 3 months [17]. A psychiatric trial used two sessions a day on five weekdays, 10 sessions in all [1]. A heart-rate-variability biofeedback trial used 10 sessions of 20 minutes over 3 weeks [18]. These are study protocols, not recommendations.

Safety and interactions

Side effects. Safety was rarely measured. A 2026 review found safety reported in 18.75% of its 48 studies and no serious adverse events noted [3]. A 2022 meta-analysis expects few adverse effects [9].

Hyperventilation. In people with dysfunctional breathing, breathing too deeply or too fast can cause breathlessness, chest tightness, dizziness, tremor and tingling [19]. The blood pressure trials used a set slow pace, usually 10 breaths a minute or fewer [11].

Upper limits. No harmful dose was reported in the trials read, and safety was rarely measured, so no safe ceiling is established [3].

Heart and lung conditions. In a 21-person trial in heart failure with reduced ejection fraction, after 3 months of device-guided slow breathing, no patient had heart-failure worsening, rehospitalisation or death during 6 months of follow-up [17]. The trial was small. In asthma, one review found quality-of-life gains from breathing exercises, but certainty ranged from moderate to very low [20].

Medicines. None of the trials read for this page tested interactions with medicines. The heart-failure trial enrolled patients already on standard drug therapy [17], and the older-adult blood pressure trial enrolled people whose hypertension was controlled and stable [2].

Pregnancy and breastfeeding. The trials read for this page did not report safety in pregnancy or breastfeeding. A 2026 review lists gestational diabetes among conditions with consistent benefit, but it was not a safety analysis [3].

Kidney, liver and bleeding disorders. No data were found for these groups.

Caveats and open questions

Blood pressure results disagree. A blinded analysis of individual patient data from three of five eligible trials found no significant reduction in office blood pressure compared with a sham device or music therapy [21]. The 2019 meta-analysis reports high variability between trials [11]. In an earlier review of device-guided breathing, five of the eight trials were sponsored by or involved the device maker, and the blood pressure effect disappeared once they were excluded [7].

Most results are on markers such as blood pressure and heart rate variability rather than on clinical outcomes [11][9]. Heart rate variability did not change in a 12-week trial that reported lower psychological stress [8]. A single 5-minute session of bee-humming breathing did not lower blood pressure, though it changed heart rate variability [5]. A crossover trial of 14 people found that head movement with device-guided breathing reduced night-time blood pressure but not 24-hour pressure [22].

Some trials combined breathing with other techniques, such as muscle relaxation, so the effect of breathing alone is not always clear [23]. The psychiatric trial's primary outcomes, self-reported somatic well-being and arousal, were not improved, and the benefits were on secondary measures [1]. A 12-week paramedic trial reported differential dropout, which the authors say limits interpretation [13]. For dysfunctional breathing itself, a 2013 Cochrane review found no credible evidence because it included only one small trial [19].