We share what research really says, without exaggeration. What we know, and what we don't.
Each card shows what the study actually found, and its limits.
A systematic review linking breathing slower than 10 breaths per minute with higher heart rate variability and a calmer emotional state.
Limitation: Only 15 studies, and they differ widely.
Zaccaro, A., Piarulli, A., Laurino, M., et al. (2018). How breath-control can change your life: a systematic review on psycho-physiological correlates of slow breathing. Frontiers in Human Neuroscience. doi:10.3389/fnhum.2018.00353
A randomized study in which five minutes a day of breathing with a long exhale went along with a clearer positive change in mood over a month than the same time of mindfulness meditation.
Limitation: About 100 participants, conducted remotely, lasted one month.
Balban, M. Y., Neri, E., Kogon, M. M., et al. (2023). Brief structured respiration practices enhance mood and reduce physiological arousal. Cell Reports Medicine. doi:10.1016/j.xcrm.2022.100895
A meta-analysis of 223 studies finding that the rest-related part of heart rate variability rises during and after voluntary slow breathing.
Limitation: A physiological finding; it does not measure mood or anxiety.
Laborde, S., Allen, M. S., Borges, U., 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. doi:10.1016/j.neubiorev.2022.104711
A meta-analysis of 47 randomized trials finding small to moderate effects of mindfulness meditation programs on anxiety, low mood and pain.
Limitation: Not found superior to other active approaches such as exercise.
Goyal, M., Singh, S., Sibinga, E. M. S., et al. (2014). Meditation programs for psychological stress and well-being: a systematic review and meta-analysis. JAMA Internal Medicine. doi:10.1001/jamainternmed.2013.13018
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
An experimental study in which participants keeping weekly gratitude notes rated their lives more positively.
Limitation: Student sample; later studies found smaller effects.
Emmons, R. A., McCullough, M. E. (2003). Counting blessings versus burdens: an experimental investigation of gratitude and subjective well-being in daily life. Journal of Personality and Social Psychology. doi:10.1037/0022-3514.84.2.377
A meta-analysis of 94 tests finding that concrete "if this happens, I will do that" intentions are linked with goal attainment at a medium to large level.
Limitation: The effect belongs to concrete if-then plans; the same evidence does not exist for general intention statements.
Gollwitzer, P. M., Sheeran, P. (2006). Implementation intentions and goal achievement: a meta-analysis of effects and processes. Advances in Experimental Social Psychology. doi:10.1016/S0065-2601(06)38002-1
A meta-analysis of 27 studies linking gratitude practices with a small decrease in anxiety and depressive symptoms.
Limitation: The effect is small and shrinks further against other active practices.
Cregg, D. R., Cheavens, J. S. (2021). Gratitude interventions: effective self-help? A meta-analysis of the impact on symptoms of depression and anxiety. Journal of Happiness Studies. doi:10.1007/s10902-020-00236-6
A meta-analysis of 146 randomized studies finding a small but positive effect of writing about feelings.
Limitation: The effect is very small and varies between people.
Frattaroli, J. (2006). Experimental disclosure and its moderators: a meta-analysis. Psychological Bulletin. doi:10.1037/0033-2909.132.6.823
A meta-analysis linking loneliness and social isolation with worse long-term health outcomes.
Limitation: Observational data; it does not show cause and effect. Evidence for online peer support is still limited.
Holt-Lunstad, J., Smith, T. B., Baker, M., Harris, T., Stephenson, D. (2015). Loneliness and social isolation as risk factors for mortality: a meta-analytic review. Perspectives on Psychological Science. doi:10.1177/1745691614568352
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
A systematic review and meta-analysis suggesting Reiki may be better than placebo on some mood measures.
Limitation: Few studies per outcome.
Zadro, S., Stapleton, P. (2022). Does Reiki benefit mental health symptoms above placebo?. Frontiers in Psychology. doi:10.3389/fpsyg.2022.897312
A meta-analysis covering 824 adults linked Reiki with a clear decrease in anxiety.
Limitation: Results are less consistent for pre-surgery and cancer-related anxiety; most studies had no sham control.
Guo, X., Long, Y., Qin, Z., Fan, Y. (2024). Therapeutic effects of Reiki on interventions for anxiety: a meta-analysis. BMC Palliative Care. doi:10.1186/s12904-024-01439-x
In 159 patients, a single Reiki session before endoscopy was linked with lower stress and anxiety and more comfort than sham and control groups.
Limitation: Single centre, single session.
Utli, H., Vural Doğru, B. (2023). The effect of Reiki on anxiety, stress, and comfort levels before gastrointestinal endoscopy: a randomized sham-controlled trial. Journal of PeriAnesthesia Nursing. doi:10.1016/j.jopan.2022.08.010
At Çukurova University, 93 patients in the Reiki group had less surgical fear, anxiety and pain, compared with sham and control groups.
Limitation: Single centre; Reiki was given by the researcher.
Şişman, N. Y., Arslan, S. (2023). The effect of Reiki on anxiety, fear, pain and oxygen saturation in abdominal surgery patients: a randomized controlled trial. Explore. doi:10.1016/j.explore.2022.11.005
In 90 women, Reiki was linked with less pain, anxiety and need for pain relief after caesarean birth.
Limitation: The control group only rested; no sham.
Sağkal Midilli, T., Eser, İ. (2015). Effects of Reiki on post-cesarean delivery pain, anxiety, and hemodynamic parameters: a randomized, controlled clinical trial. Pain Management Nursing. doi:10.1016/j.pmn.2014.09.005
A meditation focused on the heart and crown chakras was linked with lower exam anxiety in 100 nursing students.
Limitation: Control was usual preparation; short follow-up.
Varvani Farahani, P., et al. (2026). The effect of meditation on exam anxiety of nursing students: a randomized clinical trial. Irish Journal of Medical Science. doi:10.1007/s11845-026-04308-z
In 16 people over 5 months, heart rate variability was linked with changes in solar and geomagnetic activity.
Limitation: An observational study; it does not show energy being guided to the chakras.
Alabdulgader, A., McCraty, R., Atkinson, M., et al. (2018). Long-term study of heart rate variability responses to changes in the solar and geomagnetic environment. Scientific Reports. doi:10.1038/s41598-018-20932-x
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