HRV Biofeedback Trials Summarized: Anxiety, Depression, Blood Pressure and Asthma

What HRV biofeedback is, in the studies

Heart rate variability (HRV) is the natural beat-to-beat change in heart rate. In heart rate variability biofeedback (HRVB), a device gives real-time feedback from heart data. In one protocol type described by a methods review, the device shows the person a suggested breathing rate. [1] The same review describes HRVB as based on breathing at an individual's resonance frequency. [1] A mechanism review links breathing at about 0.1 Hz (roughly 6 breaths a minute) with larger cardiac oscillations. [2] This page summarizes trials only. For the technique, devices and consumer products, see HRV biofeedback: evidence and limits and resonance-frequency breathing.

This is information, not medical advice. HRVB is studied as an add-on, usually with a trained provider. It does not replace medicines or therapy. Stop any breathing practice if you feel dizzy, tingly, faint or more anxious, and never practice while driving, bathing or near water. In the United States, call 911 for an emergency and 988 for a mental health crisis.

Summary of the reviews

Anxiety and stress

A 2017 meta-analysis found 24 studies with 484 participants. Compared with a control condition, biofeedback had an effect size (Hedges' g) of 0.83, a large effect on self-reported stress and anxiety. [3] The authors said more well-controlled studies are needed. [3] A broader 2020 review of 58 studies found a small to moderate effect favoring HRVB that did not differ from other effective treatments, with the largest effects for anxiety, depression and anger. [10] Effects were larger against inactive controls (such as waitlists) than against active controls, though significant for both. [10]

Why this matters: a waitlist comparison cannot separate the breathing from attention, expectation and support. The effect against active comparisons is the more cautious number.

Depression

A 2021 meta-analysis of 14 randomized trials (794 participants) found a medium effect on depressive symptoms (g = 0.38). [4] The prediction interval, the range where a new trial's result may fall, stretched below zero, so a future trial could find no benefit. [4] A 2023 meta-analysis of 9 studies (428 participants) with other medical conditions found a similar direction, but the link between mood change and HRV change was not significant. [5] HRVB is not a replacement for depression treatment; see a clinician for persistent low mood.

PTSD

A meta-analysis of five studies in 95 military service members found a moderate to large reduction in PTSD symptoms. The authors noted the studies were small, which limits interpretation. [6] The broader review found the smallest effects for PTSD, sleep and quality of life. [10] For trauma-related breathing, see breathing practices for PTSD and trauma.

Blood pressure and the heart

A systematic review of HRVB in people with heart disease reported lower readmissions than psychological education, and lower blood pressure in pre-hypertensive patients. It also said a standard breathing protocol is needed in future studies, and that data on mortality in coronary artery disease are scarce. [7] A review of chronic conditions reported positive effects on hypertension among other outcomes, no adverse effects reported, and called for further investigation. [11] Blood pressure itself is covered at slow breathing and blood pressure.

Asthma

In a trial of 68 adults with mild or moderate asthma, HRVB and a comparison condition (relaxing music, relaxed paced breathing and EEG biofeedback) produced similar improvements in a lung challenge test, symptoms and quality of life. [8] The authors concluded HRVB should not be considered an alternative to controller medicines such as inhaled steroids, and measurements showed increased upper airway (vocal cord) resistance during biofeedback periods in both groups. [8] A single short session protected lung function against a stress test in people with asthma, a small physiological study. [12] Do not stop or change asthma medicines for biofeedback.

Why results are hard to compare

• Many studies did not report enough information to repeat their method. A review of 143 HRVB studies found almost two thirds omitted details such as breathing duration or body position. [1]
• Protocols differ: some fit a personal breathing rate, others use one preset rate. [1]
• Participants know they are receiving biofeedback, so expectation may contribute.
• The abstracts we read did not report who funded the trials or whether authors teach or sell the method. We did not read full texts.
• Children and teens: reviewers say HRVB has not been widely explored in this age group. [9]

For general trial problems see breathwork trial quality and bias.