Put on your headphones and choose a tone. The kaleidoscope changes colour with the sound.
Start at a low volume. Don't listen while driving or doing anything that needs your attention.
When your left ear hears a 200 Hz tone and your right ear a 205 Hz tone, the brain perceives the 5 Hz difference as a slow pulse. This is called a binaural beat; Gerald Oster described it in detail in 1973. The difference can be matched to brainwave ranges: delta (0.5-4 Hz), theta (4-8 Hz), alpha (8-13 Hz), beta (13-30 Hz).
Whether it truly "entrains" brainwaves is debated: a 2023 systematic review found the EEG results inconsistent. On the other hand, a 2019 meta-analysis found small to moderate effects on anxiety. So it may go along with a feeling of relaxation for some people, not for everyone.
A meta-analysis of 36 publications found that listening to natural sounds goes along with less stress and a more positive mood. A Cochrane review also suggests that listening to music before bed may help sleep quality. Still, the truest measure is your own ear.
A 2016 study in Nature showed that light flickering 40 times per second increased gamma waves in the visual cortex of mice. Sakin's light meditations do not flicker; they are made of slowly flowing colours and are not based on this study. We designed them as a calm visual space that is easy on the eyes.
Each card shows what the study actually found, and its limits.
The foundational article describing how the brain perceives the difference between two tones in each ear as a beat.
Limitation: Not an effect study; it explains how the perception arises.
Oster, G. (1973). Auditory beats in the brain. Scientific American. doi:10.1038/scientificamerican1073-94
A meta-analysis of 22 studies finding small to moderate effects of binaural beats on attention, anxiety and pain perception.
Limitation: Studies are small and varied; later replications are inconsistent.
Garcia-Argibay, M., Santed, M. A., Reales, J. M. (2019). Efficacy of binaural auditory beats in cognition, anxiety, and pain perception: a meta-analysis. Psychological Research. doi:10.1007/s00426-018-1066-8
A systematic review finding inconsistent evidence that binaural beats "entrain" brainwaves on EEG.
Limitation: Most included studies are small and differ from one another.
Ingendoh, R. M., Posny, E. S., Heine, A. (2023). Binaural beats to entrain the brain? A systematic review of the effects of binaural beat stimulation on brain oscillatory activity. PLOS ONE. doi:10.1371/journal.pone.0286023
An EEG study showing 4 Hz and 10 Hz binaural beats increase alpha-band coherence between the two auditory cortices.
Limitation: The authors read this as the brain combining the two ears' sounds, not as brainwave entrainment; no behavioural effect was seen.
Solcà, M., Mottaz, A., Guggisberg, A. G. (2016). Binaural beats increase interhemispheric alpha-band coherence between auditory cortices. Hearing Research. doi:10.1016/j.heares.2015.09.011
A brain imaging study in which natural sounds, compared with artificial ones, went along with outward attention and a rest response.
Limitation: Small sample, laboratory setting.
Gould van Praag, C. D., Garfinkel, S. N., Sparasci, O., et al. (2017). Mind-wandering and alterations to default mode network connectivity when listening to naturalistic versus artificial sounds. Scientific Reports. doi:10.1038/srep45273
A Cochrane review of 13 studies (1,007 people) finding that listening to music probably raises subjective sleep quality.
Limitation: Participants knew their group; it is about music, not nature sounds.
Jespersen, K. V., Pando-Naude, V., Koenig, J., Jennum, P., Vuust, P. (2022). Listening to music for insomnia in adults. Cochrane Database of Systematic Reviews. doi:10.1002/14651858.CD010459.pub3
A meta-analysis of 36 publications linking natural sounds with less stress and annoyance and a more positive mood.
Limitation: Studies vary and most are short laboratory listening sessions.
Buxton, R. T., Pearson, A. L., Allou, C., et al. (2021). A synthesis of health benefits of natural sounds and their distribution in national parks. PNAS. doi:10.1073/pnas.2013097118
A study showing light flickering 40 times per second increased gamma waves in the visual cortex of mice.
Limitation: Done in mice. Sakin's light meditations do not flicker and are not based on this study.
Iaccarino, H. F., Singer, A. C., Martorell, A. J., et al. (2016). Gamma frequency entrainment attenuates amyloid load and modifies microglia. Nature. doi:10.1038/nature20587
A small study reporting that music tuned to 528 Hz went along with changes in some stress-related measures.
Limitation: Only 9 participants; very limited evidence.
Akimoto, K., Hu, A., Yamaguchi, T., Kobayashi, H. (2018). Effect of 528 Hz music on the endocrine system and autonomic nervous system. Health. doi:10.4236/health.2018.109088
Stay inside the sound a little.
Breathing exercises and daily practices are always free.
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