Why vibration on the wrist?

Your skin has receptors tuned to vibration. The ones that feel a watch's buzz best respond to fast vibrations of about 100–300 per second.

• Dougherty P (2020). Somatosensory Systems (Neuroscience Online, Section 2, Chapter 2). Neuroscience Online, McGovern Medical School at UTHealth (open textbook). https://nba.uth.tmc.edu/neuroscience/m/s2/chapter02.html
• Bolanowski & Zwislocki (1984). Intensity and frequency characteristics of pacinian corpuscles. I. Action potentials. Journal of Neurophysiology 51(4):793–811. doi:10.1152/jn.1984.51.4.793
• Bolanowski et al. (1988). Four channels mediate the mechanical aspects of touch. Journal of the Acoustical Society of America 84(5):1680–1694. doi:10.1121/1.397184
• Bartel & Mosabbir (2021). Possible mechanisms for the effects of sound vibration on human health. Healthcare 9(5):597. doi:10.3390/healthcare9050597

Gentle, slow touch has its own nerve pathway to brain areas tied to how we feel. Whether a watch's vibration uses it is not known.

• McGlone et al. (2014). Discriminative and affective touch: sensing and feeling. Neuron 82(4):737–755. doi:10.1016/j.neuron.2014.05.001
• McGlone (2026). C-low threshold mechanoreceptors: a novel target for health-tech in an increasingly touch-deprived world. Philosophical Transactions of the Royal Society B 381(1958):20240463. doi:10.1098/rstb.2024.0463

How felt sound might affect the body is still being worked out; researchers have ideas, but they are not yet tested.

• Bartel & Mosabbir (2021). Possible mechanisms for the effects of sound vibration on human health. Healthcare 9(5):597. doi:10.3390/healthcare9050597

In one study, a felt stringed instrument and calm music both left people in a better mood, and neither beat the other.

• Sandler et al. (2017). Relaxation – induced by vibroacoustic stimulation via a body monochord and via relaxation music – is associated with a decrease in tonic electrodermal activity and an increase of the salivary cortisol level in patients with psychosomatic disorders. PLOS ONE 12(1):e0170411. doi:10.1371/journal.pone.0170411

Researchers are studying music with felt vibration in clinical settings; the early results are small pilot studies and say nothing about Carpemind.

• Sigurdardóttir et al. (2019). A pilot study on high amplitude low frequency–music impulse stimulation as an add-on treatment for depression. Brain and Behavior 9(10):e01399. doi:10.1002/brb3.1399

When students lay on a vibrating bed with music, they felt calmer, but so did those who heard the same music without the vibration.

• Kantor et al. (2022). Effect of low frequency sound vibration on acute stress response in university students—pilot randomized controlled trial. Frontiers in Psychology 13:980756. doi:10.3389/fpsyg.2022.980756

A steady, unchanging buzz is not more relaxing than calm sound alone, and may even be slightly stimulating. That is why Carpemind's vibration follows a rhythm and pauses.

• Vilímek et al. (2022). The effect of low frequency sound on heart rate variability and subjective perception: a randomized crossover study. Healthcare 10(6):1024. doi:10.3390/healthcare10061024

Research on felt sound is young: the studies are small and differ a lot, so there are no firm answers yet.

• Kantor et al. (2022). Exploring vibroacoustic therapy in adults experiencing pain: a scoping review. BMJ Open 12(4):e046591. doi:10.1136/bmjopen-2020-046591

In a lab study, feeling the beat of a favourite song on the wrist while hearing it seemed to add a little to the music. The vibration on its own did little.

• Lad et al. (2022). Feeling the music: the feel and sound of songs attenuate pain. British Journal of Pain 16(5):518–527. doi:10.1177/20494637221097786

In one study, a slow, heartbeat-like pulse on the wrist helped people feel calmer before a stressful task. It was a single, small, industry-funded study.

• Azevedo et al. (2017). The calming effect of a new wearable device during the anticipation of public speech. Scientific Reports 7:2285. doi:10.1038/s41598-017-02274-2

Breathing guides that vibrate work best when the pace fits you, which is why you can choose the length of a session and close your eyes.

• Miri et al. (2020). PIV: placement, pattern, and personalization of an inconspicuous vibrotactile breathing pacer. ACM Transactions on Computer-Human Interaction 27(1). doi:10.1145/3365107

Research suggests a gentle vibration that paces slow breathing can help people feel less tense after a stressful moment.

• Miri et al. (2020). Evaluating a personalizable, inconspicuous vibrotactile (PIV) breathing pacer for in-the-moment affect regulation. Proceedings of CHI 2020. doi:10.1145/3313831.3376757

Not everyone likes being guided by vibration; many people prefer a visual or moving cue. That is why the calm session also shows a growing and shrinking circle.

• Honinx et al. (2025). The effectiveness and user preferences of two tactile breathing devices in reducing stress in stressed individuals: a mixed methods study. International Journal of Clinical and Health Psychology 25(3):100603. doi:10.1016/j.ijchp.2025.100603

Vibration seems to help most when it is tied to your breathing, rather than playing on its own.

• Fani et al. (2023). Neurophysiological changes associated with vibroacoustically-augmented breath-focused mindfulness for dissociation: targeting interoception and attention. Psychological Medicine 53(16):7550–7560. doi:10.1017/s0033291723001277
• McDermott et al. (2025). Find your rhythm and regulate: breath-synced vibration feedback during breath-focused mindfulness reduces respiration variability in trauma-exposed adults. Journal of Anxiety Disorders 112:103008. doi:10.1016/j.janxdis.2025.103008

People differ in which vibration feels calming, and the one you like may matter more than any setting.

• Hallihan & Siegle (2022). Effect of vibroacoustic stimulation on athletes recovering from exercise. European Journal of Applied Physiology 122(11):2427–2435. doi:10.1007/s00421-022-05026-x

Breathing about six times a minute (in for 4 s, out for 6 s, as in the calm session) lets heart rate rise and fall smoothly with each breath, a pattern linked to a relaxed state.

• Lehrer & Gevirtz (2014). Heart rate variability biofeedback: how and why does it work?. Frontiers in Psychology 5:756. doi:10.3389/fpsyg.2014.00756

Many studies show that a few minutes of slow breathing shifts heart rhythm towards a calmer pattern and helps people feel more relaxed.

• Laborde et al. (2022). Effects of voluntary slow breathing on heart rate and heart rate variability: a systematic review and a meta-analysis. Neuroscience & Biobehavioral Reviews 138:104711. doi:10.1016/j.neubiorev.2022.104711
• Zaccaro et al. (2018). How breath-control can change your life: a systematic review on psycho-physiological correlates of slow breathing. Frontiers in Human Neuroscience 12:353. doi:10.3389/fnhum.2018.00353

Slow-breathing practice with heart-rhythm feedback has been studied widely, with small to moderate benefits for how people feel and perform.

• Lehrer et al. (2020). Heart rate variability biofeedback improves emotional and physical health and performance: a systematic review and meta analysis. Applied Psychophysiology and Biofeedback 45(3):109–129. doi:10.1007/s10484-020-09466-z

Listening to music is one of the best-studied ways to unwind: across many trials, it helped people feel less stressed.

• de Witte et al. (2020). Effects of music interventions on stress-related outcomes: a systematic review and two meta-analyses. Health Psychology Review 14(2):294–324. doi:10.1080/17437199.2019.1627897

Music you like may nudge your heart rhythm a little towards calm; your own taste seems to matter more than any special sound.

• Zhang et al. (2026). Effect of music intervention on heart rate variability: a systematic review and meta-analysis of randomized controlled trials. Frontiers in Psychology 17:1750786. doi:10.3389/fpsyg.2026.1750786
• Flater et al. (2026). Music therapy and vagally mediated heart rate variability: a systematic review and narrative synthesis. International Journal of Psychophysiology 219:113288. doi:10.1016/j.ijpsycho.2025.113288

Slower music tends to calm the body and faster music to lift it. Pauses matter too: a short silence was the most relaxing moment in one study. Your heart does not simply copy the beat.

• Bernardi et al. (2006). Cardiovascular, cerebrovascular, and respiratory changes induced by different types of music in musicians and non-musicians: the importance of silence. Heart 92(4):445–452. doi:10.1136/hrt.2005.064600
• Koelsch & Jäncke (2015). Music and the heart. European Heart Journal 36(44):3043–3049. doi:10.1093/eurheartj/ehv430

Binaural beats may help some people feel calmer, but the idea that they tune your brain waves is not supported by most studies.

• Garcia-Argibay et al. (2019). Efficacy of binaural auditory beats in cognition, anxiety, and pain perception: a meta-analysis. Psychological Research 83(2):357–372. doi:10.1007/s00426-018-1066-8
• Ingendoh et al. (2023). Binaural beats to entrain the brain? A systematic review of the effects of binaural beat stimulation on brain oscillatory activity, and the implications for psychological research and intervention. PLOS ONE 18(5):e0286023. doi:10.1371/journal.pone.0286023

There is no good evidence that 432 Hz, 528 Hz or other 'miracle frequencies' do anything special. Carpemind picks music for its tempo and feel, not for a tuning.

• Calamassi & Pomponi (2019). Music tuned to 440 Hz versus 432 Hz and the health effects: a double-blind cross-over pilot study. Explore 15(4):283–290. doi:10.1016/j.explore.2019.04.001
• Akimoto et al. (2018). Effect of 528 Hz music on the endocrine system and autonomic nervous system. Health 10(9):1159–1170 (Scientific Research Publishing). doi:10.4236/health.2018.109088

You may read about 40 Hz sound for the brain: that is early medical research with conflicting results, and Carpemind does not use it.

• Iaccarino et al. (2016). Gamma frequency entrainment attenuates amyloid load and modifies microglia. Nature 540(7632):230–235. doi:10.1038/nature20587
• Chan et al. (2022). Gamma frequency sensory stimulation in mild probable Alzheimer's dementia patients: results of feasibility and pilot studies. PLOS ONE 17(12):e0278412. doi:10.1371/journal.pone.0278412
• Soula et al. (2023). Forty-hertz light stimulation does not entrain native gamma oscillations in Alzheimer's disease model mice. Nature Neuroscience 26(4):570–578. doi:10.1038/s41593-023-01270-2

Sound too low to hear has shown no effect on sleep or mood in careful trials, either good or bad.

• Marshall et al. (2023). The health effects of 72 hours of simulated wind turbine infrasound: a double-blind randomized crossover study in noise-sensitive, healthy adults. Environmental Health Perspectives 131(3):037012. doi:10.1289/ehp10757
• Ascone et al. (2021). A longitudinal, randomized experimental pilot study to investigate the effects of airborne infrasound on human mental health, cognition, and brain structure. Scientific Reports 11:3190. doi:10.1038/s41598-021-82203-6
• Baliatsas et al. (2016). Health effects from low-frequency noise and infrasound in the general population: is it time to listen? A systematic review of observational studies. Science of the Total Environment 557–558:163–169. doi:10.1016/j.scitotenv.2016.03.065

Vibration platforms in gyms have not been shown to calm or lift mood through any particular frequency.

• Chawla et al. (2022). Effect of whole-body vibration on depression, anxiety, stress, and quality of life in college students: a randomized controlled trial. Oman Medical Journal 37(4):e408. doi:10.5001/omj.2022.72
• Faes et al. (2023). Beyond physiology: acute effects of side-alternating whole-body vibration on well-being, flexibility, balance, and cognition using a light and portable platform. A randomized controlled trial. Frontiers in Sports and Active Living 5:1090119. doi:10.3389/fspor.2023.1090119