our science

Everything we make is grounded in peer-reviewed research, selected by our chief scientific officer, an NHS doctor.

our sources

our app (synappro breathe) 17 references · breathing and autonomic regulation

synappro breathe was developed with reference to published research on mindful breathing, autonomic regulation, stress, anxiety, cardiovascular function and related breathing techniques.

relax · 4-7-8

  1. Vierra J, Boonla O, Prasertsri P. Effects of sleep deprivation and 4-7-8 breathing control on heart rate variability, blood pressure, blood glucose, and endothelial function in healthy young adults. Physiol Rep. 2022 Jul;10(13):e15389.
  2. Nielsen C, Katz S, Parker M, et al. A student-driven mindfulness curriculum for first-year osteopathic medical students: a pilot study. J Osteopath Med. 2023 Jul 12;123(10):485-492.
  3. Aktaş GK, İlgin VE. The effect of deep breathing exercise and 4-7-8 breathing techniques applied to patients after bariatric surgery on anxiety and quality of life. Obesity Surgery. 2023;33(3):920-929.

focus · 4-4-4-4

  1. Grossman D, Christensen LW. On Combat: The Psychology and Physiology of Deadly Conflict in War and in Peace. 3rd ed. Belleville, IL: PPCT Research Publications; 2008.
  2. Röttger S, Theobald DA, Abendroth J, et al. The effectiveness of combat tactical breathing as compared with prolonged exhalation. Appl Psychophysiol Biofeedback. 2021;46:19-28.
  3. Bouchard S, Bernier F, Boivin E, Morin B, Robillard G. Using biofeedback while immersed in a stressful videogame increases the effectiveness of stress management skills in soldiers. PLoS One. 2012;7(4):e36169.

ease · 4-0-6

  1. Zaccaro A, Piarulli A, Laurino M, Garbella E, Menicucci D, Neri B, Gemignani A. How breath-control can change your life: a systematic review on psycho-physiological correlates of slow breathing. Frontiers in Human Neuroscience. 2018;12:353.
  2. Van Diest I, Verstappen K, Aubert AE, Widjaja D, Vansteenwegen D, Vlemincx E. Inhalation/exhalation ratio modulates the effect of slow breathing on heart rate variability and relaxation. Applied Psychophysiology and Biofeedback. 2014;39:171-180.
  3. Laborde S, Iskra M, Zammit N, Borges U, You M, Sevoz-Couche C, Dosseville F. Slow-paced breathing: influence of inhalation/exhalation ratio and of respiratory pauses on cardiac vagal activity. Sustainability. 2021;13(14):7775.

general breathing research

  1. Russo MA, Santarelli DM, O'Rourke D. The physiological effects of slow breathing in the healthy human. Breathe. 2017;13(4):298-309.
  2. Morgan SP, Lengacher CA, Seo Y. A systematic review of breathing exercise interventions: an integrative complementary approach for anxiety and stress in adult populations. Journal of Holistic Nursing. 2024;42(3):215-230.
  3. Jerath R, Edry JW, Barnes VA, Jerath V. Physiology of long pranayamic breathing: neural respiratory elements may provide a mechanism that explains how slow deep breathing shifts the autonomic nervous system. Medical Hypotheses. 2006;67(3):566-571.

alternate nostril breathing

  1. Nivethitha L, Mooventhan A, Manjunath NK. Effects of various Prāṇāyāma on cardiovascular and autonomic variables. Ancient Science of Life. 2016;36(2):72-77.
  2. Nam TG, Jeong HI, Kim KH, Jang I. Effectiveness of alternative nostril breathing on blood pressure: a systematic review and meta-analysis of randomized controlled trials. Complementary Medicine Research. 2023;31(5):449-459.

diaphragmatic breathing

  1. Hopper SI, Murray SL, Ferrara LR, Singleton JK. Effectiveness of diaphragmatic breathing for reducing physiological and psychological stress in adults: a quantitative systematic review. JBI Database of Systematic Reviews and Implementation Reports. 2019;17(9):1855-1876.

sighing

  1. Vlemincx E, Van Diest I, Van den Bergh O. A sigh of relief or a sigh to relieve: the psychological and physiological relief effect of deep breaths. Physiology & Behavior. 2016;165:127-135.
  2. Vlemincx E, et al. Take a deep breath: the relief effect of spontaneous and instructed sighs. Physiology & Behavior. 2010;101(1):67-73.
our music 5 references · music, stress and psychophysiology

Our music was developed with reference to published research on music, stress reduction and psychophysiological response.

  1. de Witte M, da Silva Pinho A, Stams GJ, Moonen X, Bos AER, van Hooren S. Music therapy for stress reduction: a systematic review and meta-analysis. Health Psychology Review. 2022;16(1):134-159.
  2. de Witte M, Spruit A, van Hooren S, Moonen X, Stams GJ. Effects of music interventions on stress-related outcomes: a systematic review and two meta-analyses. Health Psychology Review. 2020;14(2):294-324.
  3. Bernardi L, Porta C, Sleight P. Cardiovascular, cerebrovascular, and respiratory changes induced by different types of music in musicians and non-musicians: the importance of silence. Heart. 2006;92(4):445-452.
  4. Gomez P, Danuser B. Relationships between musical structure and psychophysiological measures of emotion. Emotion. 2007;7(2):377-387.
  5. Bernardi L, Porta C, Casucci G, Balsamo R, Bernardi NF, Fogari R, Sleight P. Dynamic interactions between musical, cardiovascular, and cerebral rhythms in humans. Circulation. 2009;119(25):3171-3180.
synappro displays (loop & teams) 11 references · visual perception, motion sickness and photosensitive safety

Our displays were developed with reference to published research on fractal geometry and visual preference, vection and visually induced motion sickness, pattern glare and visual discomfort, and photosensitive epilepsy safety guidelines.

  1. Hägerhäll CM, Laike T, Taylor RP, Küller M, Küller R, Martin TP. Investigations of human EEG response to viewing fractal patterns. Perception. 2008;37(10):1488-1494.
  2. Taylor RP, Spehar B. Fractal fluency: an intimate relationship between the brain and processing of fractal stimuli. In: The Fractal Geometry of the Brain. Springer; 2016:485-496.
  3. Keshavarz B, Philipp-Muller AE, Hemmerich W, Riecke BE, Campos JL. The effect of visual motion stimulus characteristics on vection and visually induced motion sickness. Displays. 2019;58:71-81.
  4. Guo X, Nakamura S, Fujii Y, Seno T, Palmisano S. Effects of luminance contrast, averaged luminance and spatial frequency on vection. Experimental Brain Research. 2021;239(12):3507-3525.
  5. Wilkins A, Nimmo-Smith I, Tait A, McManus C, Della Sala S, Tilley A, Arnold K, Barrie M, Scott S. A neurological basis for visual discomfort. Brain. 1984;107(4):989-1017.
  6. Evans BJW, Stevenson SJ. The Pattern Glare Test: a review and determination of normative values. Ophthalmic and Physiological Optics. 2008;28(4):295-309.
  7. Napadow V, Sheehan JD, Kim J, LaCount LT, Park K, Kaptchuk TJ, Rosen BR, Kuo B. The brain circuitry underlying the temporal evolution of nausea in humans. Cerebral Cortex. 2013;23(4):806-813.
  8. Yang, Guo, So, Cheung. Effects of eye fixation on visually induced motion sickness: are they caused by changes in retinal slip velocity? Proceedings of the Human Factors and Ergonomics Society Annual Meeting. 2011;55(1):1220-1224.
  9. Golding JF, Rafiq A, Keshavarz B. Predicting individual susceptibility to visually induced motion sickness by questionnaire. Frontiers in Virtual Reality. 2021;2:576871.
  10. Vogel H. A better way to construct the sunflower head. Mathematical Biosciences. 1979;44(3-4):179-189.
  11. Epilepsy Foundation of America consensus statement; Web Content Accessibility Guidelines (WCAG) 2.3.1.
synappro workshop 18 references · breathing, stress, mood and the cost of poor mental health

Our workshop was developed with reference to published research on structured breathing, slow and exhale-focused breathing, stress, mood and physiological arousal, and on the scale and cost of mental ill health in the UK.

mood and physiological arousal

  1. Yilmaz Balban MY, Neri E, Kogon MM, Weed L, Nouriani B, Jo B, Holl G, Zeitzer JM, Spiegel D, Huberman AD. Brief structured respiration practices enhance mood and reduce physiological arousal. Cell Reports Medicine. 2023;4(1):100895.

4-7-8 breathing

  1. Vierra J, Boonla O, Prasertsri P. Effects of sleep deprivation and 4-7-8 breathing control on heart rate variability, blood pressure, blood glucose, and endothelial function in healthy young adults. Physiol Rep. 2022 Jul;10(13):e15389.
  2. Nielsen C, Katz S, Parker M, et al. A student-driven mindfulness curriculum for first-year osteopathic medical students: a pilot study. J Osteopath Med. 2023 Jul 12;123(10):485-492.
  3. Aktaş GK, İlgin VE. The effect of deep breathing exercise and 4-7-8 breathing techniques applied to patients after bariatric surgery on anxiety and quality of life. Obesity Surgery. 2023;33(3):920-929.

long exhale and slow breathing

  1. Röttger S, Theobald DA, Abendroth J, et al. The effectiveness of combat tactical breathing as compared with prolonged exhalation. Appl Psychophysiol Biofeedback. 2021;46:19-28.
  2. Zaccaro A, Piarulli A, Laurino M, Garbella E, Menicucci D, Neri B, Gemignani A. How breath-control can change your life: a systematic review on psycho-physiological correlates of slow breathing. Frontiers in Human Neuroscience. 2018;12:353.
  3. Van Diest I, Verstappen K, Aubert AE, Widjaja D, Vansteenwegen D, Vlemincx E. Inhalation/exhalation ratio modulates the effect of slow breathing on heart rate variability and relaxation. Applied Psychophysiology and Biofeedback. 2014;39:171-180.
  4. Laborde S, Iskra M, Zammit N, Borges U, You M, Sevoz-Couche C, Dosseville F. Slow-paced breathing: influence of inhalation/exhalation ratio and of respiratory pauses on cardiac vagal activity. Sustainability. 2021;13(14):7775.

general breathing research

  1. Russo MA, Santarelli DM, O'Rourke D. The physiological effects of slow breathing in the healthy human. Breathe. 2017;13(4):298-309.
  2. Morgan SP, Lengacher CA, Seo Y. A systematic review of breathing exercise interventions: an integrative complementary approach for anxiety and stress in adult populations. Journal of Holistic Nursing. 2024;42(3):215-230.
  3. Jerath R, Edry JW, Barnes VA, Jerath V. Physiology of long pranayamic breathing: neural respiratory elements may provide a mechanism that explains how slow deep breathing shifts the autonomic nervous system. Medical Hypotheses. 2006;67(3):566-571.

diaphragmatic breathing

  1. Hopper SI, Murray SL, Ferrara LR, Singleton JK. Effectiveness of diaphragmatic breathing for reducing physiological and psychological stress in adults: a quantitative systematic review. JBI Database of Systematic Reviews and Implementation Reports. 2019;17(9):1855-1876.
  2. Ma X, Yue ZQ, Gong ZQ, Zhang H, Duan NY, Shi YT, Wei GX, Li YF. The effect of diaphragmatic breathing on attention, negative affect and stress in healthy adults. Frontiers in Psychology. 2017;8:874.

sighing

  1. Vlemincx E, Van Diest I, Van den Bergh O. A sigh of relief or a sigh to relieve: the psychological and physiological relief effect of deep breaths. Physiology & Behavior. 2016;165:127-135.
  2. Vlemincx E, et al. Take a deep breath: the relief effect of spontaneous and instructed sighs. Physiology & Behavior. 2010;101(1):67-73.

mental health and its cost in the UK

  1. Mind. Mental health facts and statistics. London: Mind.
  2. Mental Health Foundation. Stress: are we coping? London: Mental Health Foundation; 2018.
  3. Cardoso F, McHayle Z. The economic and social costs of mental ill health: review of methodology and update of calculations. London: Centre for Mental Health; 2024.

synappro helps you understand and practise ways to look after your wellbeing. We do not treat, cure or diagnose. If you are struggling, please see our mental health resources. Questions about the evidence? Ask us.