The Research Behind the Breathing Programs

This app's breathing programs are paced-breathing patterns defined by a ratio of inhale : hold (retain) : exhale : hold (sustain) repeated over a number of cycles. The specific counts aren't arbitrary — most map onto breathing techniques that have been studied for their effects on the autonomic nervous system, heart rate variability (HRV), mood, anxiety, and sleep.

This document summarizes that research and ties it to the app's presets. Every study below links to its paper. Full citations are in the references.

Note on evidence quality. Most of these are small acute studies (often 15–60 participants, single sessions) measuring physiological markers like HRV. They consistently point the same direction, but this is wellness guidance, not medical advice. People with cardiovascular or respiratory conditions, or who are pregnant, should talk to a clinician before doing long breath-holds.

The one unifying idea: slow breathing shifts you toward "rest and digest"

Almost every program here slows the breath below the ~12–16 breaths/min of normal rest. Slowing the breath — especially with a longer exhale — increases vagal (parasympathetic) activity, which shows up as higher HRV, lower heart rate, lower blood pressure, and reduced anxiety.

• A 2025 Scientific Reports study, Luo et al., "The effect of slow breathing in regulating anxiety", combined paced breathing with an uncertainty-threat task and found slow breathing measurably lowered anxiety, with distinct EEG signatures.
• Iwabe et al. (2025) showed slow-paced breathing (4 s in / 6 s out) reduced state anxiety and buffered people against aversive images afterward.
• The mechanism is laid out in Noble & Hochman (2019): breathing near 0.1 Hz (~6 breaths/min) drives baroreflex resonance, synchronizing heart-rate and blood-pressure rhythms and maximizing HRV.
• Malhotra et al. (2021) and Balint et al. (2025) confirm these acute HRV increases hold even in clinical populations (the latter in hospitalized COVID-19 pneumonia patients, using a 4 s in / 6 s out pace).

So the broad claim the app rests on is well supported: slow, paced breathing acutely calms the nervous system. The interesting differences are in how the counts are arranged.

Coherent breathing (5-5, ~6 breaths/min) → program: Coherent

The app's Coherent program uses [5, 0, 5, 0] — a 5-second inhale and 5-second exhale, no holds, which is exactly 6 breaths per minute (0.1 Hz). This is the single most-studied rate in the literature, often called resonance frequency or resonance paced breathing.

• Steffen et al. (2017) experimentally isolated ~6 breaths/min as the driver of HRV improvement, along with better mood and lower systolic blood pressure.
• Schwerdtfeger et al. (2019) review why 0.1 Hz oscillations matter for heart–brain coupling.
• A 2024 systematic review, Vukojević, Vater & Laborde (17 studies, 810 participants), reports broad psychological benefits (attention, sleep, relaxation, lower anxiety/depression) and physiological ones (higher baroreflex gain, lower blood pressure).
• Bates et al. (2026) used fMRI (N=147) to show resonance breathing at 0.1 Hz increases connectivity in the brain's central autonomic network, especially the insula.

Takeaway for the app: Coherent is the best-evidenced preset for raising HRV and is a safe, general-purpose default. One caveat from You, Laborde et al. (2023): the optimal rate varies per person within roughly 5–7 breaths/min, so 5-5 is a sensible center but not magic for everyone.

Extended exhale (exhale longer than inhale) → programs: Clear Mind, Relax 1, Relax 3, Anti-Stress, Calming 3, Decision-Making

Several programs deliberately make the exhale longer than the inhale:

The key study here is Bae et al. (2021): increasing the exhale-to-inhale ratio to 2:1 raised vagal HRV markers (RMSSD, HF-HRV) without even changing the overall breathing rate — and the effect persisted for minutes afterward. This directly validates the design choice behind the extended-exhale programs.

Röttger et al. (2020) adds nuance by comparing prolonged exhalation against tactical (box-style) breathing under stress: prolonged exhalation lowered arousal and supported better performance when active coping was required, while box breathing suited passive coping. In other words, extended-exhale patterns are a good fit for "calm down and act" situations — which is essentially what Decision-Making targets.

4-7-8 breathing → program: Relax 2 (4-7-8)

Relax 2 is the classic 4-7-8: inhale 4, hold 7, exhale 8 ([4,7,8,0]). It combines a long exhale and a substantial breath-hold, and it's popular as a sleep aid.

• Mualifah & Herawati (2026), a controlled study of 110 students, found 4-7-8 practiced twice daily for two weeks significantly improved sleep quality (large effect size on the PSQI).
• Zhang & Zhu (2025) measured acute drops in heart rate and the LF/HF ratio (toward parasympathetic dominance) during 4-7-8 breathing.
• It's also been used for acute pain and anxiety, e.g. Azizah et al. (2025) on postoperative pain.

Important caveat: the head-to-head study Marchant et al. (2025) found that while 4-7-8 is effective, 6 breaths/min (Coherent) raised HRV more — though 6 bpm also carried a higher risk of over-breathing (lowering CO₂ too much). 4-7-8's longer hold and exhale may make it gentler on CO₂ levels, which is part of why it feels settling before sleep.

Box breathing (4-4-4-4) → program: Box

Box uses equal [4,4,4,4] — inhale, hold, exhale, hold, all 4 seconds. It's the "tactical breathing" used in military and first-responder training.

• Ovs et al. (2026) found a 6-week box breathing program (with wearable HR feedback) produced large improvements in athletes' real-time decision-making and lowered resting heart rate.
• Jones et al. (2026), an RCT in tactical cadets, showed box breathing accelerated parasympathetic reactivation (HF-HRV recovery) after maximal exertion.

But two comparison studies temper the enthusiasm for box breathing as a calming tool specifically:

• Marchant et al. (2025): box ("square") breathing raised HRV less than 6 bpm.
• Kasap & Aydın (2025): after high-intensity exercise, box breathing produced higher post-exercise heart rate and perceived exertion than 6 bpm — i.e., the breath-holds add a mild stressor.

Takeaway: Box is excellent for focus, composure, and performance under pressure, but if the goal is pure relaxation, Coherent or an extended-exhale program may edge it out.

Breath retention / holds (kumbhaka) → programs: Power, Harmony, Calming 1, Calming 2, Fire, Retention, Swooning, Energizing, Anti-Appetite

Many programs build in holds, either after the inhale (lungs full — retain) or after the exhale (lungs empty — sustain). Examples: Power [1,2,2,0], Harmony [1,3,2,1], Swooning [5,10,7,0] (a long full-lung hold), Retention [2,0,2,12] and Fire [3,0,5,12] (long empty-lung holds).

This is the least precisely studied part of the app. Breath retention is studied mostly under the umbrella of kumbhaka pranayama rather than at the specific counts the app uses:

• Saisupriya et al. (2020) studied a 1:3:2 inhale:hold:exhale ratio (6:18:12 s) with retention and found it shifted participants toward parasympathetic dominance (lower HR, higher RMSSD/HF) — a pattern echoing the app's holds-heavy designs.
• Nivethitha et al. (2017) found breath retention (kumbhaka) and forceful breathing (bhastrika) have opposite effects on cerebral blood flow — a reminder that holds are physiologically active, not neutral pauses.

Takeaway: The general principle (holds + slow breathing → parasympathetic shift, used for energy/focus in shorter forms and deep relaxation in longer forms) is supported, but the exact counts in Power, Fire, Retention, Swooning, etc. are extrapolations from the broader pranayama tradition rather than directly validated. Longer empty-lung holds (Fire, Retention) are the most demanding and least studied — worth a gentle in-app note for beginners.

Structured multi-technique breathwork (zooming out)

A landmark RCT from Stanford, Balban et al. (2023) in Cell Reports Medicine, compared three 5-minute daily breathwork practices against mindfulness meditation over a month:

1. Cyclic sighing (emphasizing prolonged exhalation),
2. Box breathing (equal in/hold/out/hold), and
3. Cyclic hyperventilation with retention.

All improved mood and lowered arousal, but exhale-focused cyclic sighing produced the biggest mood improvement and respiratory-rate reduction — again underscoring the recurring theme that the exhale is where the calming happens. This supports the app's emphasis on extended-exhale and long-exhale-with-hold programs (Clear Mind, Relax 1/2/3, Calming series).

Cyclic Sighing (the physiological sigh) → program: Cyclic Sighing

The app's Cyclic Sighing program uses a double inhale (a full nasal inhale, then a second short "top-up" sip) followed by a long, slow exhale through the mouth — encoded with the optional second-inhale phase ([2, 0, 5, 0, 1]). This is the "physiological sigh," the body's own reset breath.

• The headline evidence is the Stanford RCT Balban et al. (2023), Cell Reports Medicine (N=114): five minutes a day of cyclic sighing for a month produced the greatest improvement in positive mood and the largest reduction in respiratory rate of the practices tested — beating box breathing, cyclic hyperventilation, and mindfulness meditation.
• The mechanism — a double inhale re-inflates collapsed alveoli and a long exhale offloads CO₂ and boosts vagal tone — is reviewed in the popular-science write-ups of the same lab's work and is consistent with the broader extended-exhale findings (Bae 2021).

Takeaway: this is arguably the single best-evidenced short practice for mood specifically, which is why the app features it near the top. It's gentle, needs no breath-holding, and works in five minutes.

Alternate-nostril breathing → program: Nadi Shodhana

Nadi Shodhana alternates the breath between the nostrils (closed with the fingers), with optional holds ([4,0,4,0] → [5,5,5,0] across levels). Because the app can't control your nostrils, the technique is guided in the program's "how to" hint while the timer paces the breath.

• Sinha et al. (2013), J. Clinical & Diagnostic Research found alternate-nostril breathing shifted healthy young adults toward parasympathetic dominance (lower heart rate and blood pressure, improved autonomic balance).
• The systematic review Zaccaro et al. (2018), "How Breath-Control Can Change Your Life" places alternate-nostril breathing within the wider slow-breathing literature, linking it to increased HRV, parasympathetic activity, and calmer emotional state.

Yogic slow-breathing: Ujjayi, Dirga & Sitali → programs: Ujjayi, Dirga, Sitali (and Triangle)

Three traditional pranayama round out the slow-breathing set:

• Ujjayi ("ocean breath") — slow, even nasal breathing with a slight throat constriction ([5,0,5,0] → [6,2,8,0]). The gentle resistance naturally slows and smooths the breath toward the resonance range.
• Dirga ("three-part breath") — deep diaphragmatic breathing filling belly, ribs, then chest ([6,0,6,0] → [8,0,8,0]), a long even breath that recruits the diaphragm.
• Sitali ("cooling breath") — inhaling through a curled tongue with a longer exhale ([4,0,6,0] → [5,2,7,0]); traditionally used to cool and calm.
• Triangle — equal inhale–hold–exhale with no empty-lung pause ([4,4,4,0] → [6,6,6,0]), a gentler relative of Box for steady focus.

The broad evidence base for these is the slow-breathing literature summarized in Zaccaro et al. (2018) and Noble & Hochman (2019): breathing slowly and evenly (with a longer or controlled exhale) raises HRV and parasympathetic tone. Caveat: these are traditional techniques validated at the level of "slow yogic breathing" rather than at each app's exact counts — the counts are sensible, tradition-aligned defaults rather than separately trialed protocols.

Practical mapping: which program, which goal?

Gaps and honest caveats

• Long breath-holds (Power, Fire, Retention, Swooning, Energizing) are the least directly validated at the app's specific counts — studied mostly as generic kumbhaka pranayama.
• Over-breathing risk: faster or deeper paced breathing (including 6 bpm if done with large tidal volumes) can lower CO₂ uncomfortably (Marchant 2025). Encourage gentle, not forceful, breaths.
• Acute vs. lasting effects: most evidence is for immediate effects during or just after a session. Durable benefits (sleep, trait anxiety) appear with regular daily practice over weeks (Mualifah 2026, Balban 2023).

Compiled from the Semantic Scholar (Asta) research corpus. See the references for full citations.