How Stress, Fatigue & Sleep Are Measured
How adaptogen trials measure stress, fatigue and sleep, with questionnaires, clinician ratings and cortisol tests, and why a changed lab number is not the same as feeling better.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
Short answer. Trials measure stress, fatigue and sleep in two main ways. Most use questionnaires that people fill in about how they feel, or scales a clinician completes. Some also measure a biomarker, most often cortisol. A questionnaire score reflects how a person says they feel. A cortisol reading is a lab number. They answer different questions, and a trial that reports both can find a change in one and not the other. If you are worried about fatigue, weight loss or low mood, a clinician can look for causes; a supplement is not a test or a treatment.
How the sources define the terms
A clinical outcome directly measures whether people in a trial feel or function better, or live longer, according to the US Food and Drug Administration. [1] A biomarker or surrogate endpoint is a substitute measure used when the real outcome is hard to measure; the FDA says extensive evidence must build up before a surrogate can be accepted in place of a clinical outcome. [1] Cortisol is a hormone that MedlinePlus says helps the body respond to stress; it can be measured in blood, urine or saliva. [2] For the wider idea, see biomarkers vs clinical outcomes.What is measured and how
| What | Common tool in trials | What the source says | Limits |
|---|---|---|---|
| Perceived stress | Perceived Stress Scale (PSS) | Authors of a 2012 ashwagandha trial describe it as perhaps the most commonly used scale for self-perception of stress, with ten items rated by frequency or extent. [3] | Self-reported; reflects how the person feels at the time |
| Stress, anxiety, depression symptoms | DASS-21; Hamilton Anxiety Rating Scale | A 2019 ashwagandha trial describes DASS-21 as a validated self-report measure and the Hamilton scale as clinician-administered. [4] | Clinician ratings depend on the rater; both are scores, not diagnoses |
| Fatigue | Fatigue Severity Scale | Developed in 1989 and tested in 25 people with multiple sclerosis, 29 with lupus and 20 healthy adults. [5] | Tested in specific groups, not in stressed healthy adults |
| Sleep quality | Pittsburgh Sleep Quality Index (PSQI) | A self-rated questionnaire covering a one-month interval, with 19 items giving seven component scores. [6] | Self-report of the past month |
| Sleep amount | Self-report vs wrist actigraphy | In 2,036 adults, self-reported sleep duration correlated poorly with actigraphy (r=0.263), and 58% of those who reported short sleep were reclassified by actigraphy. [7] | Questionnaire answers can differ from objective measures |
| Stress biology | Cortisol (blood, saliva, urine) | MedlinePlus says levels vary during the day, with blood typically drawn in the morning when levels are normally highest, and that stress and exercise can raise them. [2] | Timing, exercise and stress on the day can change the reading |
Biomarker versus how you feel
A 2012 ashwagandha trial in 64 adults with chronic stress measured serum cortisol and several questionnaires. The authors reported lower scores on all the stress scales and lower serum cortisol than placebo at day 60. [3] A 2026 meta-analysis of 23 randomized trials (1,706 patients) found lower cortisol with oral ashwagandha than placebo, but the authors noted heterogeneity and limited data for some endpoints and called for more standardized trials. [8] Evidence label: promising but limited, and the cortisol result is a biomarker finding, not proof of better coping.We did not find a source in our reading that describes cortisol as an accepted replacement for how people feel in trials of adaptogens. Proper evidence not found on that point: we read the sources listed on this page and searched the FDA surrogate-endpoint pages and PubMed abstracts on 2026-10-23.
Frequently asked questions
What is the Perceived Stress Scale?
A ten-item questionnaire about how often a person feels stressed. It is widely used in trials, and it records the person's own perception. [3]
Does a lower cortisol result mean an adaptogen worked?
Not by itself. Cortisol is a biomarker, and MedlinePlus notes it varies through the day and rises with stress and exercise. [2] A clinical outcome is whether people feel or function better. [1]
Can a home cortisol test show whether I need an adaptogen?
The Endocrine Society says tests offered for "adrenal fatigue" are not supported by good scientific studies. [10] Ask a clinician about testing for a real adrenal condition.
Are sleep questionnaires reliable?
They capture how people feel they slept. In one large study, self-reported sleep duration and wrist-worn actigraphy agreed poorly. [7]
What should I look for in a trial report?
Which scales were used, whether there was an objective measure, how many people, how long, and who paid for it; see study limitations and funding.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Limits and uncertainty
- Most results rest on self-report. Questionnaires and clinician scales record how a person says they feel, not an independent measurement.
- Trials do not line up neatly. A meta-analysis of 12 ashwagandha trials rated certainty low and reported very high heterogeneity (I² 93.8% for anxiety). [9]
- A cortisol change is not a diagnosis. The Endocrine Society says there is no test that can detect "adrenal fatigue", and that tests offered for it are not supported by good scientific studies. [10] See adrenal fatigue and adrenal support claims and cortisol, adrenal fatigue and what the science supports.
Safety and when to ask a clinician
References
- U.S. Food and Drug Administration. Surrogate Endpoint Resources for Drug and Biologic Development. Page read 2026-10-23. Read 2026-10-23.
- MedlinePlus (National Library of Medicine). Cortisol Test. Page read 2026-10-23. Read 2026-10-23.
- Chandrasekhar K, Kapoor J, Anishetty S. A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root in reducing stress and anxiety in adults. Indian J Psychol Med. 2012. PubMed 23439798, full text at PMC3573577. Read 2026-10-23.
- Lopresti AL, Smith SJ, Malvi H, Kodgule R. An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: a randomized, double-blind, placebo-controlled study. Medicine (Baltimore). 2019. PubMed 31517876, full text at PMC6750292. Read 2026-10-23.
- Krupp LB, LaRocca NG, Muir-Nash J, Steinberg AD. The fatigue severity scale. Application to patients with multiple sclerosis and systemic lupus erythematosus. Arch Neurol. 1989. PubMed 2803071. Read 2026-10-23.
- Buysse DJ, Reynolds CF 3rd, Monk TH, Berman SR, Kupfer DJ. The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Res. 1989. PubMed 2748771. Read 2026-10-23.
- Self-reported versus actigraphy-assessed sleep duration in the ELSA-Brasil study: analysis of the short/long sleep duration reclassification. Sleep Breath. 2022. PubMed 34750722. Read 2026-10-23.
- Hormonal modulation with Withania somnifera: systematic review and meta-analysis of randomized-controlled trials. Planta Med. 2026. PubMed 41740946. Read 2026-10-23.
- Akhgarjand C, Asoudeh F, Bagheri A, et al. Does ashwagandha supplementation have a beneficial effect on the management of anxiety and stress? A systematic review and meta-analysis of randomized controlled trials. Phytother Res. 2022. PubMed 36017529. Read 2026-10-23.
- Endocrine Society. Adrenal Fatigue. Patient resource, January 25, 2022. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH). Ashwagandha: Usefulness and Safety. Last updated March 2023. Read 2026-10-23.