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.

6 studies

Yoga

Yoga for anxiety: A systematic review and meta-analysis of randomized controlled trials

Cramer H, Lauche R, Anheyer D, et al.

Depression and Anxiety · 2018

This review pooled randomized controlled trials of yoga for people with anxiety disorders or elevated anxiety levels. Eight trials with 319 participants, mostly in their 30s, were included. Compared with no treatment, yoga showed small short-term reductions in anxiety, and compared with active comparison groups the effects were larger. There were also small effects on depression compared with no treatment. Importantly, no effects were found for people whose anxiety disorder was formally diagnosed under DSM criteria; the benefits appeared in those diagnosed by other methods and in people with elevated anxiety but no formal diagnosis. Only three trials reported side effect data, and these did not show more injuries with yoga. The authors call the evidence preliminary and ask for more high-quality trials, and the small number of studies is the main limitation.

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Yoga · Somatic and Movement Healing

Yoga for chronic non-specific low back pain

Wieland LS, Skoetz N, Pilkington K, et al.

Cochrane Database of Systematic Reviews · 2022

This Cochrane review assessed yoga for adults with chronic low back pain that has no specific identified cause. It included 21 randomized trials with 2,223 participants, mostly women in their 40s and 50s practicing Iyengar, hatha or viniyoga styles. Compared with no exercise, yoga produced small improvements in back function and pain at three months, smaller than what is usually considered clinically important, along with a small improvement in physical and mental quality of life and possibly a higher chance that people rated their back as improved. Compared with other back-focused exercise, yoga made little or no difference. Yoga was also associated with more adverse events, mainly temporary increases in back pain. A key limitation is that participants could not be blinded, and most outcomes were self-reported.

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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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Yoga

Yoga for depression: A systematic review and meta-analysis

Cramer H, Lauche R, Langhorst J, et al.

Depression and Anxiety · 2013

This systematic review and meta-analysis examined randomized controlled trials of yoga for people with depressive disorders or elevated depression levels. Twelve trials with 619 participants were included, three of which had low risk of bias. Compared with usual care, yoga showed moderate evidence of short-term reductions in depression severity, and there was more limited evidence that yoga reduced depression compared with relaxation and with aerobic exercise. There was also limited evidence of short-term effects on anxiety compared with relaxation. Effects appeared both in people with diagnosed depression and in those with elevated symptoms. The authors suggest yoga could be considered an additional option alongside other treatment. Limitations: the trials were few and varied, long-term effects could not be analysed, and none of the trials reported data on side effects.

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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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Somatic and Movement Healing · Yoga

Yoga as an Adjunctive Treatment for Posttraumatic Stress Disorder

van der Kolk BA, Stone L, West J, et al.

The Journal of Clinical Psychiatry · 2014

This randomized controlled trial examined trauma-informed yoga for 64 women with chronic PTSD that had not responded to earlier treatment. Participants attended either a weekly one-hour trauma-informed yoga class or a supportive women's health education class for 10 weeks. In this study, 52% of the yoga group no longer met criteria for PTSD at the end, compared with 21% of the control group. Both groups improved in the first half of treatment, but the yoga group kept its gains while the control group tended to slip back. The authors suggest yoga may help people tolerate body sensations tied to fear and build emotional awareness. A limitation is the modest sample of women only, so results may not generalize to everyone.

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