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Stress

Everything in the library studied for it, medical and holistic together. Within each kind, what was shown to help comes first, strongest evidence first. What was tested and not shown to help stays on the list.

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Medication4 Supplements11 Therapies4 Practices16 Daily life9 Lab markers2

Medication

SSRIsModerateVery common

PTSD

Shown to improve PTSD symptoms in adults, with 58% responding on an SSRI against 35% on placebo.

The numbers and sources

How common: Very common: more than 1 in 10 people.
Effect: SSRIs lowered the risk of not responding against placebo (RR 0.66, 95% CI 0.59 to 0.74), with PTSD symptoms improving in 58% on an SSRI and 35% on placebo. Withdrawal from treatment was more frequent on SSRIs (RR 1.41, 95% CI 1.07 to 1.87), and 9% of people on SSRIs dropped out for adverse events [12].
Population: 1,078 adults in 8 SSRI trials for the response outcome, within a review of 66 RCTs and 7,442 participants lasting 13 days to 28 weeks [12].
Sources: [12]
Caveats: Moderate-certainty evidence. Withdrawals were higher on paroxetine than placebo when that drug was analyzed alone (RR 1.55) [12].

SSRIsModerateVery common

Staying well after symptoms improve

Shown to lower relapse in people who had improved: about 22 fewer relapses per 100 on a continued SSRI than after a switch to placebo.

The numbers and sources

How common: Very common: more than 1 in 10 people.
Effect: Across 40 studies in depression, relapse was 20.9% on a continued antidepressant and 39.7% after a switch to placebo (OR 0.38, 95% CI 0.33 to 0.43). For SSRIs the difference was 21.8 percentage points (OR 0.33, 95% CI 0.28 to 0.38) [13]. In UK primary care, relapse by 52 weeks occurred in 39% of people who stayed on their antidepressant and 56% of those who tapered to placebo (HR 2.06, 95% CI 1.56 to 2.70) [14]. In anxiety disorders, OCD and PTSD, relapse was 16.4% on a continued antidepressant and 36.4% on placebo (OR for relapse after discontinuation 3.11, 95% CI 2.48 to 3.89) [15].
Population: 8,890 people with depression in remission in 40 studies [13]; 478 adults who felt well enough to stop, mean age 54 [14]; 5,233 responders in 28 studies followed up to one year [15].
Sources: [13], [14], [15]
Caveats: These trials enrolled only people who had already improved on the drug. The discontinuation group in [14] also reported more withdrawal symptoms, and adherence to the assigned arm was 70% and 52%. [15] has no data beyond one year. Antidepressant classes were pooled in [14] and [15].

SSRIsModerate

Differences between SSRIs

Mixed results: head-to-head depression trials placed escitalopram and paroxetine among the higher response rates and fluoxetine among the lower, with small gaps once all trials were pooled.

The numbers and sources

Effect: In head-to-head depression trials, escitalopram and paroxetine were among the drugs with higher response rates than other antidepressants (odds ratios 1.19 to 1.96), and fluoxetine was among those with lower rates (0.51 to 0.84). Citalopram, escitalopram, fluoxetine and sertraline had fewer dropouts than other antidepressants (odds ratios 0.43 to 0.77). When placebo-controlled trials were added, the differences between drugs shrank [1]. In OCD, the effects of individual SSRIs were similar and did not differ statistically [5]. Across anxiety, obsessive-compulsive and stress disorders, pairwise comparisons showed only small differences between drugs [9].
Population: 116,477 adults with depression in 522 trials [1]; 3,097 adults with OCD [5]; 30,245 participants in 135 studies [9].
Sources: [1], [5], [9]
Caveats: Credible intervals were wide on most comparisons between drugs, and the certainty of evidence ranged from moderate to very low [1].

ClonidineLimited

Anxiety and PTSD

Small trials of guanfacine found no difference from placebo on anxiety scales in children or on PTSD symptoms in veterans.

Compared with placebo [11][12]

The numbers and sources

Effect: In children with anxiety disorders, anxiety rating scale scores did not differ between guanfacine and placebo, while clinicians rated more children as much improved (54.2% against 31.6%), in a study not designed for statistical testing [11]. In veterans with PTSD, guanfacine did not differ from placebo on clinician-rated or self-reported outcomes [12].
Population: 83 children aged 6 to 17 with anxiety disorders over 12 weeks [11]; a small sample of mostly male combat veterans over 8 weeks [12].
Sources: [11], [12]
Caveats: Both were pilot trials. No trial of clonidine for anxiety disorders was located.

Supplements

AshwagandhaStrong

Cortisol

Shown to lower cortisol by about 1.2 µg/dL against placebo in adults, though perceived stress did not change in the same review.

The numbers and sources

Effect: Across 7 trials, cortisol fell 1.16 µg/dL (95% CI -1.64 to -0.69) against placebo [4]. Across 23 placebo-controlled trials, cortisol fell (SMD -1.18, p < 0.04), with a possible dose-response by withanolide content [6]. A review of 23 trials of standardized root extract in healthy adults reported consistent cortisol reductions [7].
Population: Adults in RCTs of 2 weeks or more at 250 mg a day or more [4]. 1,706 adults in 23 RCTs [6]. 2,317 healthy adults [7].
Sources: [4], [6], [7]
Caveats: In the same review, cortisol fell while perceived stress did not change [4]. Cortisol is a lab marker, not a symptom. Two authors of [7] reported employment by companies, and two reported honoraria from supplement companies.

B-complex vitaminsModerate

Stress and mood

Shown to improve stress slightly in healthy and at-risk adults over 4 weeks or more, with no change in depression or anxiety. Bayer funded the review.

The numbers and sources

Effect: Across trials of 3 or more B vitamins for 4 weeks or longer, stress improved slightly (SMD 0.23, 95% CI 0.02 to 0.45). Depressive symptoms did not significantly change (SMD 0.15, 95% CI -0.01 to 0.32), nor did anxiety (SMD 0.03, 95% CI -0.13 to 0.20) [5].
Population: 16 trials with 2,015 participants, healthy and at-risk, 12 pooled [5].
Sources: [5]
Caveats: Funded by Bayer HealthCare, which sells B-complex products [5].

BacopaLimited

Anxiety and stress

Small trials found bacopa lowered anxiety and self-reported stress scores against placebo in older and middle-aged adults.

The numbers and sources

Effect: In the 12-week trial of older adults, depression and anxiety scores fell on bacopa and rose on placebo, and mood scale scores did not differ [6]. In a crossover of 17 healthy volunteers, single 320 mg and 640 mg doses produced some positive mood effects and lower cortisol during multitasking stress [9]. In adults aged 40 to 70, 12 weeks of 300 mg a day reduced self-reported stress reactivity more than placebo (p = 0.03), along with fatigue and stress after a demanding computer task [5].
Population: 54 older adults [6]. 17 healthy volunteers [9]. 87 adults with self-reported memory problems [5].
Sources: [6], [9], [5]
Caveats: Small trials. The authors of [9] call for replication in a larger sample.

SchisandraLimited

Stress and fatigue

Limited evidence: a review of Soviet-era research reports clinical trials in asthenia and stress protection in animals, without figures in its summary.

The numbers and sources

Effect: A review of research from the former USSR reports that animal studies found Schisandra protected against a broad range of stressors, including heat, cold, immobilization and low air pressure, and that numerous clinical trials reported benefit in asthenia, neurosis and astheno-depressive states. In healthy people it altered nitric oxide and cortisol levels in blood and saliva [7].
Population: Animal studies and clinical trials in the former USSR, reviewed [7].
Sources: [7]
Caveats: A narrative review, largely of older Russian-language studies. Its abstract gives no trial sizes, comparison groups or effect sizes [7]. No recent placebo-controlled trial of Schisandra alone for stress or fatigue was located.

Tongkat aliLimited

Stress hormones and mood

One small 4-week trial found lower tension, anger and saliva cortisol, and higher saliva testosterone, in moderately stressed adults.

The numbers and sources

Effect: In 63 moderately stressed adults (32 men, 31 women), 4 weeks of a hot-water root extract lowered tension (11%), anger (12%) and confusion (15%) scores, lowered salivary cortisol exposure by 16%, and raised salivary testosterone by 37% compared with placebo [6].
Population: 63 adults [6].
Sources: [6]
Caveats: One 4-week trial. The first author's listed affiliation is SupplementWatch. Cortisol and testosterone were measured in saliva.

Vitamin B6Limited

Depression symptoms

One trial found lower depression scores over 1 month only in adults with mild or worse symptoms at baseline. Anxiety and stress did not change.

The numbers and sources

Effect: Over 1 month, 100 mg of pyridoxine a day lowered depression scores more than placebo or 1,000 µg of B12 only in participants with mild or worse depression symptoms at baseline (partial η² 0.20). Anxiety and stress scores did not change [5].
Population: 267 adults from the general population, 215 of them female. 58 had mild or worse depression symptoms at baseline [5].
Sources: [5]
Caveats: One trial, and the effect appeared in a subgroup defined by baseline scores. Participants were not patients with diagnosed depression [5].

AshwagandhaModerate

Stress and anxiety

Mixed results: most reviews found lower stress and anxiety than placebo in adults, with very high variation, while one review found no change in perceived stress.

The numbers and sources

Effect: Across 12 RCTs (1,002 participants aged 25 to 48), ashwagandha lowered anxiety (SMD -1.55, 95% CI -2.37 to -0.74, I² 93.8%) and stress (SMD -1.75, 95% CI -2.29 to -1.22, I² 83.1%) compared with placebo [1]. In 14 trials in people with mental disorders, mostly anxiety disorders, anxiety fell (outlier-corrected SMD -1.13, 95% CI -1.65 to -0.60) and so did stress (SMD -0.95, 95% CI -1.46 to -0.43) [2]. A 2026 analysis of 22 trials reported lower stress (SMD -5.88, 95% CI -8.15 to -3.60) and anxiety (SMD -6.87, 95% CI -8.77 to -4.97), with stress falling further as dose rose [3]. A 2025 analysis of 6 trials found no change in Perceived Stress Scale scores (SMD -0.355, 95% CI -1.188 to 0.47) [4].
Population: Adults in 12 RCTs [1]. 360 people with mental disorders on ashwagandha and 353 controls [2]. Adults in 22 RCTs [3]. 488 participants in 7 cortisol and 6 stress trials [4].
Sources: [1], [2], [3], [4]
Caveats: Certainty was rated low for both outcomes in [1], and heterogeneity was very high. The mental disorders review was limited by few studies, substantial heterogeneity and outliers [2]. The effect sizes in [3] are several times those in the other reviews. The abstracts do not report funding of the included trials.

GABALimited

Stress

Limited evidence: a review of 14 trials found limited support for stress outcomes, and most studies had authors from industry.

The numbers and sources

Effect: A systematic review of 14 placebo-controlled trials of natural or fermented GABA found limited evidence for stress outcomes [1]. In 63 adults, 100 mg of GABA 30 minutes before mental tasks reduced the task-related drop in alpha and beta brain waves compared with placebo, and mood scores matched this [2]. In 8 male university students who play esports, 200 mg of GABA before gameplay lowered confusion and fatigue mood scores and raised game task scores compared with placebo [3].
Population: Adults in trials of single doses to several weeks [1]. 28 men and 35 women in a single-blind crossover [2]. 8 men aged 20 to 24, crossover [3].
Sources: [1], [2], [3]
Caveats: No meta-analysis was possible because outcomes varied. In 11 of the 14 studies, one or more authors worked for an industrial company [1]. All authors of the esports trial are inventors on a related patent application filed with Pharma Foods International [3].

L-TheanineLimited

Stress and anxiety

Limited evidence: acute stress fell modestly, mostly in high-bias studies, and a 28-day trial found perceived stress fell equally on placebo.

The numbers and sources

Effect: The reduction in acute stress after a single dose was modest (SMD 0.31) and largely influenced by high-risk-of-bias studies. Anxiety effects were inconsistent and not significant, except one study in psychotic anxiety at 400 mg a day for 8 weeks (SMD 0.54) [1]. A systematic review of 9 trials of pure theanine described possible stress and anxiety reduction at 200 to 400 mg a day in people under stressful conditions [4]. In 30 adults with moderate stress given 400 mg a day for 28 days, perceived stress fell 17.98% with theanine and 17.88% with placebo, and salivary cortisol did not differ between groups [5].
Population: Healthy adults and clinical groups [1][4]. 30 adults with moderate stress [5].
Sources: [1], [4], [5]
Caveats: The 28-day trial was funded by Ethical Naturals, which sells the extract tested, and one author was its employee [5].

Licorice rootUntested

Adrenal fatigue

Not studied in people for adrenal fatigue. Licorice slows the body's inactivation of cortisol, and a systematic review found no evidence adrenal fatigue is a medical condition.

No study in people. This rests on how it acts in the body.

The numbers and sources

Effect: In 7 healthy volunteers given licorice, sodium retention came with a change in cortisol metabolism showing that licorice blocks 11-beta-hydroxysteroid dehydrogenase, the enzyme that converts cortisol to inactive cortisone in the kidney [14]. A systematic review of 58 studies of cortisol and fatigue found no substantiation that adrenal fatigue is an actual medical condition [15].
Population: 7 healthy volunteers in a mechanism study [14]. 58 studies of cortisol and fatigue [15].
Sources: [14], [15]
Caveats: The enzyme effect is what raises blood pressure and lowers potassium (see Risks), and it does not show that licorice changes fatigue. No trial of licorice for fatigue or adrenal symptoms was located.

Therapies

Biofeedback and neurofeedbackModerate

Anxiety and stress, heart rate variability biofeedback

Shown to reduce self-reported stress and anxiety with a large effect (Hedges' g 0.83) against control conditions, in a meta-analysis of 24 studies.

Compared with control conditions the source abstract does not describe [9]

The numbers and sources

Effect: Heart rate variability biofeedback reduced stress and anxiety within groups (g 0.81) and against control conditions (g 0.83). The effect did not depend on study year, risk of bias, share of women, number of sessions or whether people had an anxiety disorder [9].
Population: 484 participants in 24 studies [9].
Sources: [9]
Caveats: Small studies, and outcomes were self-reported. The authors call for more well-controlled trials [9].

Massage therapyModerate

Anxiety

Shown to lower anxiety in pooled trials, including state anxiety after a single session and trait anxiety after a course of treatment.

Compared with control conditions in randomized studies the source abstract does not describe [12]; active treatments [2]

The numbers and sources

Effect: A meta-analysis of 37 randomized studies found single sessions reduced state anxiety, and a course of treatment reduced trait anxiety and depression, its largest effects, by amounts the authors likened to psychotherapy [12]. Against active comparators in pain populations, anxiety was lower with massage (SMD -0.57) [2].
Population: 37 randomized studies [12]. Trials in people with pain [2].
Sources: [12], [2]
Caveats: The older meta-analysis predates many current trials and its abstract gives no effect sizes [12]. Participants cannot be blinded to massage.

Massage therapyModerate

Stress hormones, blood pressure and immune cells after one session

Mixed results: a single session lowered blood pressure and heart rate in pooled trials, and cortisol fell in one small trial but not in pooled trials.

Compared with control conditions in randomized studies the source abstract does not describe [12]; light touch [18]

The numbers and sources

Effect: Single sessions reduced state anxiety, blood pressure and heart rate, and did not reduce cortisol [12]. In healthy adults, 45 minutes of Swedish massage produced a large drop in arginine vasopressin and a small drop in blood cortisol against light touch. Circulating lymphocytes rose (effect sizes 0.14 to 0.43) and stimulated cytokine production fell [18].
Population: 37 randomized studies [12]. Healthy adults aged 18 to 45 [18].
Sources: [12], [18]
Caveats: The trial calls its data preliminary, and these were changes over one session [18]. Lymphocyte counts in blood do not show fewer infections.

Reiki and therapeutic touchModerate

Anxiety, stress and depression, compared with sham Reiki by untrained people

Mixed results: a review of 14 sham-controlled trials found Reiki ahead of sham on some mental health symptoms, and a chemotherapy trial found comfort rose equally with sham.

Compared with sham Reiki, usually given by an untrained person taught to copy the Reiki practitioner's hand positions [2]; a sham Reiki placebo, and standard care [3]

The numbers and sources

Effect: In 14 trials with a placebo-Reiki group, Reiki showed a greater effect than placebo for some mental health symptoms. The reviewers rated the evidence high for clinically relevant stress and depression, moderate to high for clinically relevant anxiety, and low for anxiety and depression at normal levels [2]. In 189 people having chemotherapy, comfort and well-being rose after Reiki and also after sham Reiki, and did not change with standard care [3].
Population: 14 randomized placebo-controlled trials in adults [2]. 189 adults at an outpatient chemotherapy center [3].
Sources: [2], [3]
Caveats: The reviewers found few trials in each area and called the findings inconclusive, with most trials at some risk of bias [2]. The chemotherapy authors attributed the gain to one-on-one presence of a nurse [3].

Practices

MeditationStrong

Stress and distress in people without a diagnosis, against no program

Shown to lower anxiety, depression and distress in adults without a diagnosis, by about half a standard deviation, against no program or a waiting list.

Compared with no intervention [1]; control groups the source abstract does not describe [2]

The numbers and sources

Effect: Across 136 trials in nonclinical settings, mindfulness programs improved anxiety (SMD -0.56, 95% CI -0.80 to -0.33), depression (SMD -0.53, 95% CI -0.72 to -0.34), distress (SMD -0.45, 95% CI -0.58 to -0.31) and well-being (SMD 0.33, 95% CI 0.11 to 0.54) against no intervention, 1 to 6 months after the program ended. Prediction intervals for all four crossed zero [1]. In 29 studies of mindfulness-based stress reduction in healthy adults, the between-group effect was g = 0.53 (95% CI 0.41 to 0.64), with large effects on stress and moderate effects on anxiety, depression and distress, maintained at an average 19 weeks of follow-up [2].
Population: 11,605 adults in 136 trials in 29 countries, 77% women, aged 18 to 73 [1]. 2,668 healthy adults in 29 studies [2].
Sources: [1], [2]
Caveats: GRADE confidence was moderate to very low, mainly from inconsistency and high risk of bias. Only the effect on distress remained when higher-risk trials were excluded, and US trials reported smaller effects [1]. Heterogeneity was high [2]. Nobody can be blinded to a meditation course.

Cold water immersionModerate

Heart rate variability

Shown to raise heart rate variability for up to 15 minutes after cold exposure in healthy adults, alongside a slightly lower heart rate and slightly higher blood pressure.

The numbers and sources

Effect: Across 24 studies of cold water immersion and cryostimulation, heart rate variability indices rose after exposure, including RMSSD (SMD 0.61) and high-frequency power (SMD 0.46), persisting up to 15 minutes. Heart rate fell (SMD -0.16) and mean blood pressure rose (SMD 0.28) [13]. An umbrella review of post-exercise studies also reported better heart rate variability immediately after immersion [6].
Population: Healthy participants in 24 studies [13].
Sources: [13], [6]
Caveats: The pooled analysis mixes cold water immersion with whole-body and partial-body cryostimulation. Effects were measured within minutes, and the authors note they depend on individual characteristics and cooling technique [13].

MeditationModerate

Cortisol

Shown to lower cortisol in pooled trials. Blood cortisol fell only in people with a physical illness, and saliva cortisol did not fall significantly in one review.

Compared with control groups [15]; inactive controls and active controls [16]

The numbers and sources

Effect: In 10 trials using blood samples, meditation had a significant medium effect on cortisol from before to after against control, present only in samples with a somatic illness. In 21 trials using saliva the effect was small and not significant [15]. Across 34 between-group comparisons, mindfulness-based stress reduction lowered cortisol more than controls (g = -0.38, 95% CI -0.56 to -0.21), against inactive controls g = -0.42 and against active controls g = -0.29 (95% CI -0.54 to -0.04) [16].
Population: Participants in 10 randomized trials with blood samples and 21 with saliva samples [15]. 2,059 participants in 39 studies [16].
Sources: [15], [16]
Caveats: The second review pools blood and saliva samples and found unexplained heterogeneity [16]. Cortisol varies across the day, and timing of samples differs between trials.

Slow breathing and breathworkModerate

Stress, against no breathing practice

Shown to lower self-rated stress by a small to moderate amount against inactive controls such as a waiting list, in one meta-analysis.

Compared with inactive non-breathwork controls [2]

The numbers and sources

Effect: Across 12 randomized trials, breathwork lowered self-rated stress against non-breathwork controls (g = -0.35, 95% CI -0.55 to -0.14). In the 7 trials with inactive controls, g = -0.37 (95% CI -0.73 to -0.02, I² 66%) [2]. A meta-analysis of heart rate variability biofeedback, which trains breathing at a slow resonant pace, found effects larger against inactive than active controls, and significant against both [3].
Population: 785 adults in 12 trials, nonclinical and clinical samples [2]. 58 randomized trials of heart rate variability biofeedback [3].
Sources: [2], [3]
Caveats: Most trials were at moderate risk of bias, and stress was self-reported by people who knew their group [2]. The biofeedback abstract gives no subgroup sizes [3].

Slow breathing and breathworkModerate

Stress and mood, against an active comparison

Shown to lower self-rated stress slightly more than active control conditions. In one trial, 5 minutes a day of cyclic sighing lifted mood more than mindfulness meditation.

Compared with active non-breathwork controls [2]; mindfulness meditation for the same time [4]

The numbers and sources

Effect: In the 5 trials with active controls, breathwork lowered stress by g = -0.26 (95% CI -0.48 to -0.04, I² 0%) [2]. In a remote randomized trial of three 5-minute daily breathing exercises against 5 minutes of mindfulness meditation for a month, breathwork, especially exhale-focused cyclic sighing, produced a greater rise in positive mood (p < 0.05) and a greater fall in breathing rate (p < 0.05). State anxiety and negative mood fell in all groups and did not differ between breathwork and meditation [4].
Population: Participants in 5 trials [2]. 114 adults invited into a 1-month remote trial [4].
Sources: [2], [4]
Caveats: Five small trials [2]. The 1-month trial had no inactive control, participants completed about 18 to 20 of 28 days, and outcomes were self-rated [4].

Slow breathing and breathworkModerate

Heart rate variability

Shown to raise vagally mediated heart rate variability during, right after and across weeks of slow breathing practice, in one meta-analysis of 223 studies.

Compared with control conditions the source abstract does not describe [12]; mindfulness meditation [4]

The numbers and sources

Effect: Vagally mediated heart rate variability rose with voluntary slow breathing during the session (172 studies), immediately after one session (16 studies) and after multi-session programs (49 studies) [12]. In the 1-month trial of 5 minutes a day, resting heart rate variability and resting heart rate measured by a wrist wearable did not change in any group [4].
Population: 223 studies [12]. 114 adults invited into a remote trial [4].
Sources: [12], [4]
Caveats: The meta-analysis abstract gives no effect sizes [12]. Heart rate variability during slow breathing rises partly because breathing itself drives heart rhythm, so a rise in the moment is not a lasting change in resting tone.

Tai chi and qigongModerate

Stress, anxiety and depression

Shown to lower stress, anxiety and depression in pooled trials of tai chi and of qigong, against waiting list and varied controls, in trials with methodological limits.

Compared with varied control groups, including some nonrandomized studies [12]; waiting list [13]; lectures and structured movement alone [13]

The numbers and sources

Effect: Tai chi reduced stress (effect size 0.66, 95% CI 0.23 to 1.09), anxiety (0.66, 95% CI 0.29 to 1.03) and depression (0.56, 95% CI 0.31 to 0.80) and improved mood (0.45) [12]. In healthy adults, 1 to 3 months of qigong lowered anxiety (SMD -0.75, 95% CI -1.11 to -0.40, 4 trials) and stress (SMD -0.88, 95% CI -1.22 to -0.55, 3 trials) against waiting list [13].
Population: 3,817 participants in 40 studies, healthy and with chronic conditions [12]. Healthy adults in 7 trials [13].
Sources: [12], [13]
Caveats: The tai chi review pooled randomized and nonrandomized trials and noted inadequate controls [12]. The qigong review had few trials with methodological flaws [13].

YogaModerate

Anxiety, against no treatment

Shown to ease anxiety slightly against no treatment in one meta-analysis of 8 small trials, in people with raised anxiety. No effect appeared in diagnosed anxiety disorders.

Compared with no treatment [4]

The numbers and sources

Effect: Against no treatment, anxiety fell in the short term (SMD -0.43, 95% CI -0.74 to -0.11) and depression fell (SMD -0.35, 95% CI -0.66 to -0.04). No effects were found for people with anxiety disorders diagnosed by DSM criteria, only for those diagnosed by other methods and those with elevated anxiety without a formal diagnosis [4].
Population: 319 participants, mean age 30 to 38.5, in 8 trials [4].
Sources: [4]
Caveats: Few small trials with unclear risk of selection bias [4].

YogaModerate

Stress hormones, heart rate and blood fats, against active controls

Shown in one meta-analysis to lower cortisol, ambulatory systolic pressure, resting heart rate, fasting glucose and LDL cholesterol more than active control activities.

Compared with active control interventions [11]

The numbers and sources

Effect: Across 42 trials, practices including yoga postures were associated with lower evening and waking cortisol, ambulatory systolic blood pressure, resting heart rate, fasting blood glucose, cholesterol and LDL cholesterol, and higher high-frequency heart rate variability, compared with active controls [11].
Population: Participants in 42 randomized trials in various populations [11].
Sources: [11]
Caveats: The abstract gives no effect sizes and describes the interventions as heterogeneous. Some included mindfulness-based stress reduction alongside postures [11].

GroundingLimited

Stress and night-time cortisol

One uncontrolled study of 12 adults found saliva cortisol at night fell after 6 weeks of sleeping grounded, and self-reported stress eased.

Compared with before grounding, in the same people [2]

The numbers and sources

Effect: Saliva cortisol measured every 4 hours over 24 hours was significantly lower during night-time sleep at week 6 than before grounding, and 24-hour profiles trended toward a typical daily rhythm. Self-reported stress, anxiety, depression and irritability were reduced or eliminated in nearly all subjects, most clearly in women [2].
Population: 12 adults with sleep problems, pain and stress [2].
Sources: [2]
Caveats: No control group, 12 people, and cortisol was measured in saliva [2].

Infrared saunaLimited

Quality of life in type 2 diabetes

Limited evidence: quality of life, stress and fatigue scores improved after 3 months of infrared sauna in people with type 2 diabetes, in a study with no control group.

The numbers and sources

Effect: After 20-minute sessions 3 times a week for 3 months, physical health, general health and social functioning scores on the SF-36v2 improved, as did visual analogue scores for stress and fatigue [29].
Population: Patients with type 2 diabetes at one rural Canadian health center [29].
Sources: [29]
Caveats: No control group. The abstract gives no participant count, no effect sizes and no blood sugar results.

Cold water immersionModerate

Stress

Mixed results: pooled trials found lower stress 12 hours after immersion and no difference immediately, at 1 hour, at 24 hours or at 48 hours.

The numbers and sources

Effect: A meta-analysis of randomized trials in healthy adults found stress lower 12 hours after immersion (SMD -1.00, 95% CI -1.40 to -0.61), with no significant effect immediately (SMD -0.09), at 1 hour (SMD -0.29), at 24 hours (SMD -0.06) or at 48 hours (SMD 0.09) [14]. In 16 adults, cortisol was lower 180 minutes after a 15-minute immersion at 10°C than before it (p = 0.014) [15]. During 1-hour immersions at 14°C, cortisol tended to decrease [16].
Population: 3,177 participants in 11 randomized trials, at 7°C to 15°C for 30 seconds to 2 hours [14]. 16 healthy adults [15]. Young men [16].
Sources: [14], [15], [16]
Caveats: One time point of five showed an effect. The reviewers describe the evidence as limited by few trials, small samples and narrow populations [14]. The single-session studies had no control condition [15].

MeditationModerate

Stress and distress, against other active programs

Mixed results: against time-matched control programs, pooled trials found less depression and no difference in anxiety or distress. Against specific active programs, no difference was found.

Compared with nonspecific active control programs [1]; specific active programs such as exercise or other psychological programs [1]; drugs, exercise and other behavioral therapies [3]

The numbers and sources

Effect: Against nonspecific active control conditions, mindfulness programs improved depression (SMD -0.46, 95% CI -0.81 to -0.10, 6 trials), with no statistically significant evidence for anxiety or distress and no reliable data on well-being. Against specific active control conditions there was no statistically significant evidence of superiority [1]. A review of 47 trials limited to active controls found no evidence that meditation programs were better than any active treatment, including drugs, exercise and other behavioral therapies [3].
Population: Adults in nonclinical settings in 136 trials [1]. 3,515 participants with a range of clinical conditions in 47 trials [3].
Sources: [1], [3]
Caveats: Few trials made each active comparison, so a small difference could be missed [1]. "No better than" an active treatment can mean equal to it, which is how the review reads it [3].

Hyperbaric oxygen therapyLimited

PTSD

Mixed results: one unblinded trial in 35 veterans found lower PTSD scores after 60 sessions, and pooled sham-controlled military data showed a trend that did not reach significance.

The numbers and sources

Effect: In veterans with treatment-resistant PTSD, clinician-rated PTSD scores improved after 60 daily sessions and did not change in controls (net effect size 1.64, P < 0.0001), with gains in depression scores [14]. In pooled data from four sham-controlled Department of Defense studies of post-concussion symptoms, the PTSD Checklist score changed by -2.7 points (95% CI -5.8 to 0.4, p = 0.09) in favor of hyperbaric oxygen [5]. Two of those trials individually found no difference from sham on the same checklist [3][4].
Population: 35 veterans randomized, 29 completed, control group untreated [14]. 254 service members [5].
Sources: [14], [5], [3], [4]
Caveats: The positive trial had no sham, and its participants knew their group [14]. The military trials enrolled people for post-concussion symptoms, not PTSD alone.

Infrared saunaLimitedStudied in women

Cortisol and stress response

One study found morning cortisol rose after the first post-exercise infrared sauna in female athletes, a response that had disappeared after 6 weeks of regular use.

The numbers and sources

Effect: Salivary cortisol rose by 5.1 ± 8.6 nmol/L the morning after the first session in the sauna group (p = 0.017) and not in controls. Heart rate after the session was 61 against 55 beats a minute. In the sixth week the cortisol change was -1.8 ± 7.6 nmol/L [22].
Population: 40 female team sport athletes, pair-matched, using 10 minutes at 50°C after training [22].
Sources: [22]
Caveats: One study. Cortisol was measured around two exercise sessions, not as a measure of everyday stress.

SaunaLimited

Heart rate variability

One trial found no added change in heart rate variability when a 15-minute sauna followed exercise for 8 weeks, compared with exercise alone.

The numbers and sources

Effect: No heart rate variability index differed significantly between exercise plus sauna and exercise alone after 8 weeks, including RMSSD, SDNN and resting heart rate [31].
Population: 38 sedentary adults aged 49 ± 9 with at least one cardiovascular risk factor, in three groups [31].
Sources: [31], [3]
Caveats: One small trial, drawn from the same study as the blood pressure and fitness findings in [3].

Daily life

Physical activityStrong

Depression and anxiety symptoms in trials

Shown to lower depression and anxiety symptoms by a medium amount in trials across many groups, including people with major depression, in reviews rated low in quality.

Compared with usual care [13]; active controls such as usual care or a placebo tablet [14]

The numbers and sources

Effect: Across 97 reviews, physical activity had medium effects on depression (median effect size -0.43), anxiety (-0.42) and psychological distress (-0.60, 95% CI -0.78 to -0.42), with larger effects at higher intensity [13]. In major depression, walking or jogging (g -0.62, 95% credible interval -0.80 to -0.45) and mixed aerobic exercise (g -0.43) reduced symptoms, with effects in proportion to the intensity prescribed [14].
Population: 128,119 participants in 1,039 trials within 97 reviews [13]. 14,170 people with major depression in 218 trials [14].
Sources: [13], [14]
Caveats: Most reviews were rated critically low in quality [13]. Only one depression trial was at low risk of bias, and participants could not be blinded [14].

Time in natureStrong

Mood, anxiety and depressive feelings

Shown to ease negative mood, anxiety and depressive feelings and raise positive mood after time in nature, in several meta-analyses rating study quality mostly low.

Compared with control conditions, mostly passive [7]; control groups [8]; built environments [9]; before the forest bathing, in the same people [6]; a 90-minute walk in an urban setting [10]

The numbers and sources

Effect: Across 30 reviews, nature-based programs lowered anxiety (SMD -0.83, 95% CI -1.19 to -0.47), depressive symptoms (SMD -0.72) and negative affect (SMD -0.61), and raised positive affect (SMD 0.52). Physiological measures did not rise significantly (SMD 0.24, 95% CI -0.19 to 0.67) [7]. An umbrella review found lower tension (SMD -0.87) and negative affect (SMD -0.51) and higher positive affect (SMD 0.98) and wellbeing (SMD 0.40), at moderate credibility [8]. Short visits to natural settings had a small effect on depressive mood (mean g -0.29) [9]. After forest bathing, tension-anxiety and depression-dejection scores fell [6]. A 90-minute nature walk lowered rumination and activity in a brain region tied to it, and an urban walk did not [10].
Population: 3,870 primary studies in 30 reviews [7]. 344 studies in 28 reviews [8]. 33 studies [9]. 11 studies [6]. Healthy adults in one trial [10].
Sources: [7], [8], [9], [6], [10]
Caveats: Most primary studies used passive controls, short follow-up and self-report, and were rated at high risk of bias [7][9]. Only 10 of 91 associations had moderate credibility [8]. Heterogeneity was large [9].

GardeningModerate

Stress and anxiety

Shown to lower self-rated stress with horticultural therapy in one meta-analysis, without changing physiological measures. A community gardening trial found larger falls in stress and anxiety.

Compared with a control group the abstract does not describe [6]; a waiting list for a community garden plot [7]

The numbers and sources

Effect: Horticultural therapy improved psychological stress measures against control, with no significant effect on physiological measures. A total of 100 to 500 minutes gave larger effects [6]. People given a community garden plot had greater reductions in perceived stress and anxiety from spring to autumn than those kept on the waiting list [7].
Population: Trials of horticultural therapy in varied populations [6]. 291 adults new to gardening in Denver and Aurora, Colorado, 82% women [7].
Sources: [6], [7]
Caveats: The meta-analysis abstract gives no pooled sizes [6]. Stress and anxiety were secondary outcomes in the trial and were self-rated [7].

SmokingModerate

Mood after quitting

Linked to small improvements in depression, anxiety and stress after quitting, in a Cochrane review of mostly cohort data rated very low to moderate in certainty.

Compared with people who continued to smoke [19]

The numbers and sources

Effect: Against continuing to smoke, quitting was linked to lower anxiety (SMD -0.28, 95% CI -0.43 to -0.13), depression (SMD -0.30, 95% CI -0.39 to -0.21), mixed anxiety and depression (SMD -0.31) and stress (SMD -0.19), and more positive affect (SMD 0.22). New mixed anxiety and depression was less common in quitters (OR 0.76, 95% CI 0.66 to 0.86). Results were similar in people with mental illness [19].
Population: 102 studies with over 169,500 adults who smoked, followed at least 6 weeks [19].
Sources: [19]
Caveats: All studies were judged at serious risk of bias from confounding that changes over time, and there was some sign of publication bias [19]. People whose mood improves may find it easier to quit, which is reverse causation.

Time in natureModerate

Stress and cortisol

Shown to lower salivary cortisol slightly in forest groups in one meta-analysis, and serum cortisol fell after forest visits in two small trials in men.

Compared with urban groups [1]; people with lower greenspace exposure [2]; the group sent to a city area [3]; the day before forest therapy, in the same men [4]

The numbers and sources

Effect: Salivary cortisol was lower in forest groups than urban groups after the intervention (MD -0.05 μg/dL, 95% CI -0.06 to -0.04, I² 88%), and also before it (MD -0.08 μg/dL). In all but two of 22 studies, cortisol was lower after forest time than in comparison groups or than before [1]. Across observational and intervention studies, greenspace exposure was linked to lower salivary cortisol (-0.05, 95% CI -0.07 to -0.04) [2]. After a two-night forest trip, serum cortisol was lower than in a group sent to a city, as were interleukin-6 and tumor necrosis factor alpha [3]. In middle-aged men with high-normal blood pressure, serum cortisol and urinary adrenaline were lower after forest therapy than the day before [4].
Population: 22 studies, 8 pooled [1]. 103 observational and 40 interventional studies [2]. 20 healthy male university students, randomized [3]. Middle-aged men with high-normal blood pressure [4].
Sources: [1], [2], [3], [4]
Caveats: The forest groups' cortisol was already lower before the visit, which the reviewers tie to anticipation and placebo effects [1]. Studies were short, small and mostly in Japan, and nobody can be blinded to a forest. The serum trials studied only men [3][4].

Time in natureModerate

Blood pressure and heart rate

Shown to lower systolic blood pressure by about 3 mmHg and diastolic by about 2 mmHg in forest settings, in one meta-analysis of 20 trials, with heart rate also lower.

Compared with non-forest environments [5]; people with lower greenspace exposure [2]; before the forest bathing, in the same people [6]; control conditions, mostly passive [7]

The numbers and sources

Effect: Systolic blood pressure was lower in the forest than in non-forest environments (MD -3.15 mmHg, 95% CI -4.12 to -2.18, I² 1%), as was diastolic pressure (MD -1.75 mmHg, 95% CI -2.38 to -1.13) [5]. Greenspace exposure was linked to lower diastolic pressure (-1.97 mmHg) and heart rate (-2.57 beats a minute) [2]. Heart rate fell after forest bathing (MD -4.00, 95% CI -6.90 to -1.09) at very low certainty [6]. Across reviews, nature-based programs lowered heart rate (SMD -0.70, 95% CI -1.17 to -0.23) [7].
Population: 732 participants in 20 trials, 17 in Japan [5]. 143 studies [2]. 11 studies [6]. 30 reviews in a second-order meta-analysis [7].
Sources: [5], [2], [6], [7]
Caveats: Trials were short, and 17 of the 20 were in Japan [5]. Walking, quiet and cleaner air come with forest time and cannot be separated from it. No trial located tested whether the drop lasts.

Time in natureModerate

Blue spaces: coasts, lakes and rivers

Linked to more physical activity and restoration with more blue space nearby or more contact with it, in one meta-analysis. Living closer was not linked to restoration.

Compared with people living farther from, with less, or with less contact with blue space [13]; comparisons the source does not describe [14]

The numbers and sources

Effect: Living closer to blue space was linked to more physical activity (Cohen's d 0.122). More contact with blue space was linked to more restoration (d 0.191, 95% CI 0.084 to 0.298). Shorter distance was not linked to restoration (d 0.123, 95% CI -0.037 to 0.284) or social interaction [13]. A review of 33 therapeutic blue space programs found mostly positive or weak links with mental health and wellbeing, and very few findings on physical health [14].
Population: 50 studies [13]. 33 intervention studies in people with a defined need [14].
Sources: [13], [14]
Caveats: Mostly observational. The program review gave no pooled estimates [14]. Effects are small.

Shift workLimited

Redesigning shift schedules

Limited evidence: switching to faster or forward-rotating shifts, or letting workers choose their shifts, improved health or work-life balance in small, mostly uncontrolled studies.

Compared with the previous schedule, in experimental and quasi-experimental studies with or without a control group [1]

The numbers and sources

Effect: Across 26 studies, no type of schedule change was consistently harmful. Three types had beneficial effects on health, work-life balance or both: switching from slow to fast rotation, changing from backward to forward rotation (day, then evening, then night), and self-scheduling of shifts [1].
Population: Shift workers in 26 experimental and quasi-experimental studies from any country [1].
Sources: [1]
Caveats: The review gave a narrative synthesis with no pooled numbers, and the authors raised concerns about how far the evidence generalizes [1].

Sleep timingLimited

Shifting night owls to an earlier schedule

One trial moved night owls' sleep and wake times about 2 hours earlier and found less depression and stress and better morning reaction time and grip strength.

Compared with a control group the abstract does not describe [1]

The numbers and sources

Effect: Earlier wake and sleep times, fixed meal times, limits on caffeine and timed exercise advanced sleep and wake timing by about 2 hours, measured by actigraphy, dim light melatonin onset and the cortisol awakening response, with no loss of sleep duration. Self-reported depression and stress improved, and reaction time and grip strength improved in the morning hours [1].
Population: Night owls with a late sleep and wake pattern, in one randomized controlled trial in a real-world setting. The abstract does not give the head count or length [1].
Sources: [1]
Caveats: One small trial. Participants knew their group, and mood and stress were self-rated. The trial changed several habits at once, so it cannot say which mattered.

Lab markers

CortisolModerate

Cardiovascular disease

Mixed results: higher morning cortisol went with 18% more cardiovascular disease per standard deviation in pooled cohorts, while genetic studies found no clear effect on heart disease or stroke.

The numbers and sources

Effect: In two nested case-control studies, each standard deviation higher morning plasma cortisol had an odds ratio for new cardiovascular disease of 1.28 (95% CI 1.06 to 1.54), and in a meta-analysis with earlier prospective studies it was 1.18 (1.06 to 1.31). The same paper's genetic analysis gave 1.06 (0.98 to 1.15) [5]. A second genetic study found genetically predicted cortisol unrelated to ischemic heart disease (0.98, 0.93 to 1.03) or ischemic stroke (0.99, 0.91 to 1.08) [6]. A third found each standard deviation of genetically higher cortisol associated with more atrial fibrillation (1.20, 1.06 to 1.35), an association that disappeared after adjusting for genetically predicted blood pressure and waist size (0.99, 0.72 to 1.38) [7].
Population: 696 people with new cardiovascular disease and 6,680 controls in the pooled cohorts, and 122,737 coronary heart disease cases with 547,261 controls in the genetic analysis [5]. Genetic variants from a consortium of 12,597 people, applied to large outcome studies [6][7].
Sources: [5], [6], [7]
Caveats: The cohort finding is observational, and the genetic estimates disagree with one another. The genetic studies rest on a small number of variants [6][7].

CortisolLimited

Type 2 diabetes in a genetic study

One genetic study found no association between genetically predicted cortisol and type 2 diabetes.

The numbers and sources

Effect: Genetically predicted cortisol, based on six variants, had an odds ratio for type 2 diabetes of 1.00 per unit of log-transformed cortisol (95% CI 0.96 to 1.04). It was also unrelated to adiposity, blood sugar traits, blood pressure and lipids. Genetically predicted diabetes was not associated with cortisol either [6].
Population: Six variants identified in 12,597 people, applied to genome-wide studies of type 2 diabetes [6].
Sources: [6]
Caveats: One genetic study, whose authors call for replication. Genetic estimates describe lifelong differences, not the effect of a change later in life [6].