The science

The Library

The practices at Halcyon are old. The research on them is newer, and growing. These are the studies we read and return to, each with a short note in plain language and a link to the original paper. We share them to inform, not to promise, and none of it is medical advice.

13 studies

Sleep · Meditation

The effect of mindfulness meditation on sleep quality: a systematic review and meta‐analysis of randomized controlled trials

Rusch HL, Rosario M, Levison LM, et al.

Annals of the New York Academy of Sciences · 2019

This meta-analysis gathered randomized controlled trials of mindfulness meditation for people with sleep problems. It included 18 trials with 1,654 participants and analysed two kinds of comparison separately. Against established sleep treatments, mindfulness showed no difference in sleep quality, with low strength of evidence, meaning it performed about the same rather than better. Against control activities that matched time and attention, mindfulness significantly improved sleep quality, with moderate strength of evidence, both straight after the program and at follow-up. The authors suggest mindfulness meditation may help with some aspects of sleep disturbance and call for more research. A limitation is that the evidence that mindfulness is as good as established sleep treatments was rated low, so it should not be seen as a substitute for them.

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Yoga · Meditation

Yoga, mindfulness-based stress reduction and stress-related physiological measures: A meta-analysis

Pascoe MC, Thompson DR, Ski CF

Psychoneuroendocrinology · 2017

Rather than relying on how people say they feel, this meta-analysis looked at physical markers of stress. It included 42 randomised controlled trials comparing practices that involve yoga postures (asanas), with or without mindfulness-based stress reduction, against active control groups. Compared with active controls, yoga-based practices were associated with lower evening and waking cortisol, lower ambulatory systolic blood pressure, lower resting heart rate, changes in heart rate variability, and lower fasting blood glucose, total cholesterol and LDL cholesterol. The authors conclude that yoga-based practices appear to be associated with better regulation of the body's main stress systems, the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis. The main limitation is that the yoga programs studied were very different from each other, which makes it hard to say which style, dose or format matters most.

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Sound Bath · Meditation

Effects of Singing Bowl Sound Meditation on Mood, Tension, and Well-being: An Observational Study

Goldsby TL, Goldsby ME, McWalters M, et al.

Journal of Evidence-Based Complementary & Alternative Medicine · 2017

This observational study looked at how people felt before and after a Tibetan singing bowl sound meditation, a format close to what many people call a sound bath. Sixty-two women and men with an average age of about 50 took part. Compared with how they felt beforehand, participants afterward reported significantly less tension, anger, fatigue and depressed mood, and their sense of spiritual well-being increased. People who had never tried this kind of meditation before showed a larger drop in tension than those who were already familiar with it. The authors suggest singing bowl meditation may be a low-cost, low-technology way to ease tension and low mood. The key limitation is the design: there was no control group, so the changes cannot be separated from the effect of simply lying down and resting in a calm setting.

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Sleep · Meditation

Mindfulness Meditation and Improvement in Sleep Quality and Daytime Impairment Among Older Adults With Sleep Disturbances

Black DS, O’Reilly GA, Olmstead R, et al.

JAMA Internal Medicine · 2015

Sleep problems are common in older adults and often go untreated. In this randomized clinical trial, 49 adults with an average age of 66 and moderate sleep disturbance were assigned to six weeks of a mindful awareness practices program (two hours a week plus homework) or to a structured sleep hygiene education course of the same length. Sleep quality was measured with the Pittsburgh Sleep Quality Index. The mindfulness group improved more than the sleep hygiene group, with a large effect size, and also showed greater improvements in insomnia symptoms, depression symptoms and fatigue. There were no differences between groups for anxiety, stress or an inflammation marker. The main limitation is that the trial was small and measured outcomes immediately after the program, so it cannot say how long the improvement lasts.

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Meditation · Consciousness

Mindfulness practice leads to increases in regional brain gray matter density

Hölzel BK, Carmody J, Vangel M, et al.

Psychiatry Research: Neuroimaging · 2011

This study from the Lazar lab at Massachusetts General Hospital used MRI brain scans to look for structural changes after an eight-week mindfulness-based stress reduction (MBSR) program. Sixteen healthy adults who had never meditated were scanned before and after the course and compared with 17 people on a waiting list. The MBSR group showed increases in gray matter concentration in the left hippocampus, an area involved in learning and memory, and in the posterior cingulate cortex, the temporo-parietal junction and the cerebellum. These regions are associated with emotion regulation, self-referential thinking and perspective taking. The authors suggest that taking part in MBSR is associated with measurable changes in brain structure. The obvious limitation is size: with about 33 people in total and no randomization described in the abstract, the findings are best seen as early and in need of replication.

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Meditation

Mindfulness-based stress reduction for healthy individuals: A meta-analysis

Khoury B, Sharma M, Rush SE, et al.

Journal of Psychosomatic Research · 2015

Most research on mindfulness-based stress reduction (MBSR), the eight-week program developed by Jon Kabat-Zinn, has focused on people with health conditions. This meta-analysis looked instead at healthy adults, combining 29 studies with 2,668 participants. MBSR showed moderate effects both when comparing people before and after the program and when comparing MBSR groups with control groups, and the gains held at an average follow-up of 19 weeks. Effects were large for stress, moderate for anxiety, depression, distress and quality of life, and small for burnout. Increases in mindfulness and self-compassion tracked with these improvements. The main limitation is that results varied a lot across studies, likely because of differences in design, how the program was delivered and what was measured.

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Breathwork · Meditation

Brief structured respiration practices enhance mood and reduce physiological arousal

Balban MY, Neri E, Kogon MM, et al.

Cell Reports Medicine · 2023

Researchers at Stanford ran a remote randomized controlled trial comparing three daily five-minute breathing exercises with five minutes of mindfulness meditation, practiced every day for one month. The breathing styles were cyclic sighing, which stretches out the exhale; box breathing, with equal inhale, hold and exhale; and cyclic hyperventilation with breath retention. The team tracked mood, anxiety and physiological arousal, including breathing rate, heart rate and heart rate variability. Breathwork overall, and especially exhale-focused cyclic sighing, produced a greater improvement in mood and a larger drop in resting breathing rate than mindfulness meditation. The authors describe daily cyclic sighing as a promising stress management exercise. One honest limitation: the abstract reports the comparison against meditation rather than against a no-practice group, and the study ran for a single month, so longer-term effects remain open.

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Meditation

Mindfulness-Based Stress Reduction vs Escitalopram for the Treatment of Adults With Anxiety Disorders

Hoge EA, Bui E, Mete M, et al.

JAMA Psychiatry · 2023

This randomized clinical trial compared an eight-week mindfulness-based stress reduction (MBSR) course with escitalopram, a commonly prescribed medication for anxiety disorders. Adults with a diagnosed anxiety disorder were recruited at three US academic medical centers, and 208 completed the trial. It used a noninferiority design, meaning it tested whether MBSR was not meaningfully worse than the medication. In this study, anxiety severity dropped by a similar amount in both groups, and MBSR met the prespecified test for noninferiority. Fewer people in the MBSR group reported study-related side effects, and none left the MBSR group because of them. A limitation is that participants knew which treatment they received, and results apply to people willing to try either option.

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Meditation

Meditation Programs for Psychological Stress and Well-being

Goyal M, Singh S, Sibinga EMS, et al.

JAMA Internal Medicine · 2014

This systematic review and meta-analysis looked at whether meditation programs improve stress-related outcomes in adults with various health conditions. The authors screened over 18,000 citations and included 47 randomized trials with 3,515 participants, focusing on studies with active control groups to account for placebo effects. In this review, mindfulness meditation programs showed moderate evidence of small improvements in anxiety, depression and pain, and low evidence for improved stress and mental health-related quality of life. There was little or no evidence of effects on positive mood, attention, sleep, eating or weight, and meditation was not found to be better than other active treatments such as medication or exercise. The authors call for stronger study designs.

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Meditation

Efficacy of Mindfulness-Based Cognitive Therapy in Prevention of Depressive Relapse

Kuyken W, Warren FC, Taylor RS, et al.

JAMA Psychiatry · 2016

This meta-analysis combined individual patient data from 9 randomized trials, covering 1,258 people with recurrent depression, to see whether mindfulness-based cognitive therapy (MBCT) helps prevent relapse. MBCT was compared with usual care and with other active treatments, including antidepressants. In this analysis, people who received MBCT had a lower risk of depressive relapse over 60 weeks than those who did not, and a somewhat lower risk compared with other active treatments. Age, sex, education and relationship status did not change the effect, and there was some evidence that people with more severe symptoms before treatment benefited more. A limitation is that it relied on a fairly small number of trials, and one eligible study's data were unavailable.

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Meditation

Prevention of relapse/recurrence in major depression by mindfulness-based cognitive therapy.

Teasdale JD, Segal ZV, Williams JMG, et al.

Journal of Consulting and Clinical Psychology · 2000

This randomized trial was one of the first tests of mindfulness-based cognitive therapy (MBCT), a group program that teaches people who have recovered from depression to notice and step back from the thinking patterns that can pull them back into it. In this study, 145 people who had recovered from recurrent depression were randomized to their usual treatment alone or usual treatment plus MBCT, and were followed for 60 weeks. For participants with three or more past episodes of depression, about three quarters of the sample, MBCT significantly lowered the risk of relapse. For those with only two past episodes, it did not. A limitation is that benefits appeared only in a subgroup, so MBCT may suit some people better than others.

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Meditation · Yoga

Meditation and yoga for posttraumatic stress disorder: A meta-analytic review of randomized controlled trials

Gallegos AM, Crean HF, Pigeon WR, et al.

Clinical Psychology Review · 2017

This meta-analysis pooled 19 randomized controlled trials, covering 1,173 adults, that tested meditation or yoga for posttraumatic stress disorder. The researchers also checked whether results differed by type of practice, population, outcome measure, or control group. In this analysis, meditation and yoga were associated with a small to medium reduction in PTSD symptoms overall. No clear differences appeared between meditation and yoga or across populations, though smaller studies tended to show larger effects. The authors conclude these complementary approaches are promising and warrant further study. An honest limitation: the pattern of larger effects in small studies suggests that some estimates may be inflated, and these practices were studied as complements rather than replacements for established treatment.

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Ketamine-Assisted Psychotherapy · Meditation

Adjunctive Ketamine With Relapse Prevention-Based Psychological Therapy in the Treatment of Alcohol Use Disorder

Grabski M, McAndrew A, Lawn W, et al.

American Journal of Psychiatry · 2022

This phase 2 trial tested whether ketamine, combined with talk therapy, could help people with severe alcohol use disorder stay abstinent. Ninety-six adults were randomly assigned, double-blind, to three weekly ketamine or saline infusions, paired with either mindfulness-based relapse prevention therapy or alcohol education. In this study, the ketamine groups had more days without alcohol at six months than the placebo groups, an average difference of about 10%, and the largest difference was between ketamine plus therapy and saline plus education. There was no significant difference in relapse rates, and the treatment was well tolerated. The authors describe it as a proof-of-concept study with wide confidence intervals, so the results need confirming in larger trials.

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