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References

A bibliography of peer-reviewed research relevant to the breathing programs in this app. Grouped by the technique / count each program uses. Citations were gathered from the Semantic Scholar (Asta) corpus.

For a narrative overview of what this research says and how it maps to each program, see the research write-up.

Direct comparisons of the app's patterns

  1. Marchant, J., Khazan, I., Cressman, M., & Steffen, P. (2025). Comparing the Effects of Square, 4–7-8, and 6 Breaths-per-Minute Breathing Conditions on Heart Rate Variability, CO₂ Levels, and Mood. Applied Psychophysiology and Biofeedback. https://doi.org/10.1007/s10484-025-09688-z — Head-to-head test of Box (square), Relax 2 (4-7-8), and Coherent (6 bpm).

  2. Kasap, M., & Aydın, G. R. (2025). Box breathing or six breaths per minute: Which strategy improves athletes' post-HIIT cardiovascular recovery? PLoS ONE. https://pmc.ncbi.nlm.nih.gov/articles/PMC12622787 — Box (4-4-4-4) vs. 6 bpm (5-5) for recovery.

Coherent / Resonance breathing — programs: Coherent (5-5, ~6 bpm)

  1. Steffen, P. R., Austin, T., DeBarros, A., & Brown, T. (2017). The Impact of Resonance Frequency Breathing on Measures of Heart Rate Variability, Blood Pressure, and Mood. Frontiers in Public Health, 5, 222. https://doi.org/10.3389/fpubh.2017.00222

  2. Noble, D. J., & Hochman, S. (2019). Hypothesis: Pulmonary Afferent Activity Patterns During Slow, Deep Breathing Contribute to the Neural Induction of Physiological Relaxation. Frontiers in Physiology, 10, 1176. https://doi.org/10.3389/fphys.2019.01176

  3. Schwerdtfeger, A. R., Schwarz, G., Pfurtscheller, K., Thayer, J. F., Jarczok, M. N., & Pfurtscheller, G. (2019). Heart rate variability (HRV): From brain death to resonance breathing at 6 breaths per minute. Clinical Neurophysiology, 131(3), 676–693. https://doi.org/10.1016/j.clinph.2019.11.013

  4. Vukojević, B., Vater, C., & Laborde, S. (2024). The role of resonance frequency in slow-paced breathing: Systematic review. Current Issues in Sport Science, 9(2). https://doi.org/10.36950/2024.2ciss080

  5. Bates, M. E., Lesnewich, L. M., Pawlak, A., Buckman, J. F., & Gohel, S. (2026). Functional Connectivity Within the Central Autonomic Network Increases During Resonance Paced Breathing at 0.1 Hz. Psychophysiology. https://doi.org/10.1111/psyp.70263

Extended-exhale / inhale:exhale ratio — programs: Clear Mind, Relax 1, Relax 3, Anti-Stress, Calming 3, Decision-Making

  1. Bae, D., Matthews, J. J. L., Chen, J. J., & Mah, L. (2021). Increased exhalation to inhalation ratio during breathing enhances high-frequency heart rate variability in healthy adults. Psychophysiology, 58(11), e13905. https://doi.org/10.1111/psyp.13905

  2. Röttger, S., Theobald, D. A., Abendroth, J., & Jacobsen, T. (2020). The Effectiveness of Combat Tactical Breathing as Compared with Prolonged Exhalation. Applied Psychophysiology and Biofeedback, 46, 19–28. https://doi.org/10.1007/s10484-020-09485-w

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

  1. Mualifah, D., & Herawati, I. (2026). Effect of the 4-7-8 Breathing Technique on Sleep Quality in University Students: A Quasi-Experimental Controlled Study. Majalah Ilmiah Fisioterapi Indonesia. https://doi.org/10.24843/mifi.000001111

  2. Zhang, C., & Zhu, F. (2025). Research on the effectiveness of Golden light on sleep combined with 4-7-8 breathing technique. Proc. 4th Int. Conf. on Biomedical and Intelligent Systems. https://doi.org/10.1145/3745034.3745106

  3. Azizah, A. N., Santoso, B., Pratiwi, N. A., & Azizah, N. (2025). Effectiveness of Lemongrass Aromatherapy and The 4-7-8 Breathing Technique on Post Operative Pain after General Anesthesia. Jurnal Pendidikan Keperawatan Indonesia. https://doi.org/10.17509/jpki.v11i2.85911

Box / tactical breathing — program: Box (4-4-4-4)

  1. Ovs, P., Indra, A., Fefrian, Y., Rosmi, Putu, L., Ariani, T., Gede, I., & Utamayasa, I. G. D. (2026). The Synergy of Wearable Optical Heart Rate Sensor Technology and Box Breathing in Real-Time Decision Making in Precision, Explosive, and Intermittent Sports. Physical Education Theory and Methodology. https://doi.org/10.17309/tmfv.2026.1.15

  2. Jones, M. E., Smith, G., Acevedo, A. M., & Melton, B. (2026). Effectiveness of Structured Breathwork Interventions on Heart Rate Variability and Heart Rate Recovery Following Maximal Exertion in Tactical Athletes. Medicine & Science in Sports & Exercise. https://doi.org/10.1249/MSS.0000000000003972

Breath retention / kumbhaka — programs: Power, Harmony, Calming 1, Box, Fire, Retention, Swooning, Energizing

  1. Saisupriya, K., Chandrappa, S., Shetty, S., Shetty, P., Honnegowda, T., & Hiremath, L. (2020). Analysis of immediate effect of nadishodhana pranayama in the ratio of 1:3:2 on autonomic and respiratory variables in healthy individuals. Yoga Mimamsa, 52(1). https://doi.org/10.4103/ym.ym_21_19 — A 6:18:12 s (1:3:2 inhale:hold:exhale) protocol with breath retention.

  2. Nivethitha, L., Mooventhan, A., Manjunath, N., Bathala, L., & Sharma, V. (2017). Cerebrovascular hemodynamics during pranayama techniques. Journal of Neurosciences in Rural Practice, 8(1), 60–63. https://doi.org/10.4103/0976-3147.193532 — Kumbhaka (breath retention) vs. Bhastrika effects on cerebral blood flow.

General slow / deep breathing — umbrella for most programs

  1. Luo, Q., Li, X., Zhao, J., Jiang, Q., & Wei, D. (2025). The effect of slow breathing in regulating anxiety. Scientific Reports, 15. https://doi.org/10.1038/s41598-025-92017-5

  2. You, M., Laborde, S., Ackermann, S., Borges, U., Dosseville, F., & Mosley, E. (2023). Influence of Respiratory Frequency of Slow-Paced Breathing on Vagally-Mediated Heart Rate Variability. Applied Psychophysiology and Biofeedback, 48, 411–434. https://doi.org/10.1007/s10484-023-09605-2

  3. Balint, E. M., Grüner, B., Gündel, H., Haase, S., Kaw-Geppert, M., Thayer, J. F., Weimer, K., & Jarczok, M. N. (2025). Acute Effects of Slow-Paced Breathing on Measures of HRV in Hospitalized Patients With Bilateral COVID-19 Pneumonia. Psychosomatic Medicine. https://doi.org/10.1097/PSY.0000000000001354

  4. Pozzato, I., Schoffl, J., Tran, Y., Arora, M., McBain, C., Middleton, J., Cameron, I. D., & Craig, A. (2025). The effects of paced breathing on psychological distress vulnerability and heart rate variability in adults sustaining traumatic injury. Journal of Affective Disorders. https://doi.org/10.1016/j.jad.2025.01.008

  5. Iwabe, T., Miyakawa, A., Kodama, S., & Yoshida, S. (2025). Slow-paced breathing reduces anxiety and enhances midfrontal alpha asymmetry, buffering responses to aversive visual stimuli. Frontiers in Human Neuroscience. (open access: https://pmc.ncbi.nlm.nih.gov/articles/PMC12301348)

  6. Malhotra, V., Bharshankar, R., Ravi, N., & Bhagat, O. (2021). Acute Effects on Heart Rate Variability during Slow Deep Breathing. Mymensingh Medical Journal, 30(1), 208–214.

Structured breathwork (multi-technique RCTs)

  1. Balban, M. Y., Neri, E., Kogon, M. M., Weed, L., Nouriani, B., Jo, B., Holl, G., Zeitzer, J. M., Spiegel, D., & Huberman, A. D. (2023). Brief structured respiration practices enhance mood and reduce physiological arousal. Cell Reports Medicine, 4(1), 100895. https://doi.org/10.1016/j.xcrm.2022.100895 — RCT of cyclic sighing, box breathing, and cyclic hyperventilation vs. mindfulness. (NCT05304000)

Humming / Bhramari (relevant if a humming variant is added)

  1. Woo, M., & Kim, T. (2025). Effects of Slow-Paced Breathing and Humming Breathing on Heart Rate Variability and Affect: A Pilot Investigation. Physiology and Behavior. https://doi.org/10.1016/j.physbeh.2025.114972

  2. Latha, R., & Lakshmi, S. S. (2022). A study on immediate and training effect of Bhramari pranayama on heart rate variability in healthy adolescents. BioMedicine, 42(4). https://doi.org/10.51248/.v42i4.1501

  3. Chetry, D., Telles, S., & Balkrishna, A. (2026). Heart Rate Variability and Mood State Changes in Three Yoga Breathing Practices: A Randomized Crossover Trial. International Journal of Yoga Therapy. https://doi.org/10.17761/2025-D-25-00006

Alternate-nostril & yogic slow breathing — programs: Nadi Shodhana, Ujjayi, Dirga, Sitali, Triangle

  1. Sinha, A. N., Deepak, D., & Gusain, V. S. (2013). Assessment of the effects of pranayama/alternate nostril breathing on the parasympathetic nervous system in young adults. Journal of Clinical and Diagnostic Research, 7(5), 821–823. https://doi.org/10.7860/JCDR/2013/4750.2948

  2. Zaccaro, A., Piarulli, A., Laurino, M., Garbella, E., Menicucci, D., Neri, B., & Gemignani, A. (2018). How Breath-Control Can Change Your Life: A Systematic Review on Psycho-Physiological Correlates of Slow Breathing. Frontiers in Human Neuroscience, 12, 353. https://doi.org/10.3389/fnhum.2018.00353