Stress and Relaxation Research and Evidence

What this page is for

Headlines about stress, cortisol and "natural calm" often point to a study. This page shows how much research exists on several stress and relaxation topics and how to read it. More general guidance is in the Research Library.

A PubMed snapshot

PubMed is the U.S. National Library of Medicine's index of biomedical articles. The counts below were retrieved on October 22, 2026 through the NCBI E-utilities esearch service (database: pubmed, count only). Counts change daily. [1]

What the counts mean (and do not)

A count shows how much has been published, not whether a treatment works. Some records are opinion pieces, animal or lab studies, protocols or studies of other topics that happen to match a term. A big number can still hide weak studies, and a small number does not prove something is useless. For example, there are only 23 records with "adrenal fatigue" in the title or abstract, and a systematic review of 58 studies concluded there is no substantiation that it is a medical condition. [1][2]

How to judge a stress or anxiety study

1. Who was studied? Healthy adults, students, healthcare workers, people with an anxiety disorder, or people with cancer are different groups. The same practice can look different in each. For example, review findings for mindfulness differ between healthy adults and clinical groups. [3][4]
2. Compared with what? A study with no control group cannot show that a practice, rather than time or attention, helped. A review of workplace burnout programs noted that many studies had no control group or no follow-up. [5]
3. What was measured? Feeling less stressed on a questionnaire (self-reported) differs from a lab marker such as cortisol, and both differ from long-term health. A meta-analysis found lower serum cortisol with ashwagandha, but that is a marker, and the safety of long-term use is not known. [6]
4. How big and how consistent was the effect? Differences between studies can be large. The 2025 meta-analysis of yoga for stress found a moderate average effect with large differences between studies. [7]
5. How good is the evidence? Meta-analyses can still be low certainty. A 2022 analysis of ashwagandha for stress and anxiety rated certainty as low. [8]
6. Who paid and who is selling? Be careful with product-linked claims; supplement makers are responsible for safety and labeling, and products are not approved before sale. [9]
7. Are harms reported? Few meditation studies have looked for harms, so a lack of reports is not proof of safety. [10]
8. Does it say "more research is needed"? Often yes; take it as a signal that the answer is not settled. [11]

Key reviews used on these pages

• Breathwork and stress: 12 trials, small-to-medium effect, caution against hype. [12]
• Meditation programs: 47 trials, moderate evidence for anxiety and depression, low for stress. [4]
• Mindfulness-based stress reduction in healthy adults: 29 studies, moderate effects with high heterogeneity. [3]
• Yoga for perceived stress: 36 studies. [7]
• "Adrenal fatigue": systematic review of 58 studies. [2]
• Low-intensity CBT for generalized anxiety disorder: 12 trials. [13]

When to get help

Research summaries are not personal advice. If stress or anxiety interferes with your life, talk to a provider. [14] For emotional distress or thoughts of suicide in the US, call or text 988 (free, 24/7); in a life-threatening situation, call 911. [15][16] See Stress and anxiety safety and Cortisol and "adrenal fatigue".