What Does Ashwagandha Do for the Brain? Memory, Mood and How It Feels

In a 2026 meta-analysis of 20 trials and 1,249 adults, ashwagandha root extract improved memory (standardised difference 0.52), attention (0.29) and executive function (0.42) against placebo: moderate effects from small trials of 8 to 12 weeks, mostly in stressed but otherwise healthy adults.¹ For anxiety, 40 people with generalised anxiety disorder taking an SSRI fell 14 points on the Hamilton anxiety scale over 6 weeks on 1 g a day, against 8 on placebo, and five pooled trials of 254 people averaged 6 points more than placebo with results so varied that the certainty is low.^{2, 3} No trial shows it slows Alzheimer's or Parkinson's disease, none has measured dopamine in people, and the reports of feeling flat or numb come from forums, not from trials, which measured anxiety scales and not emotional range. Dose, sleep, the stress trials and the safety record are in the Wellgard ashwagandha guide.

Does ashwagandha improve memory and concentration?

The 2026 pooled analysis applied Cochrane risk-of-bias and GRADE methods to 20 placebo-controlled trials and found moderate improvements in memory, attention and executive function, alongside a small testosterone rise in men and strength gains only in people who train.¹ The largest single cognition trial gave 130 stressed adults 300 mg of a sustained-release root extract or placebo once a day for 90 days, with memory on a computerised test battery as the primary outcome: memory improved against placebo, with lower stress, cortisol and sleep scores as secondary outcomes.⁴ Two limits apply throughout: the trials are short, so nothing is known about years of use, and most were run at a few Indian centres with industry funding.

Does ashwagandha help with anxiety?

In people with diagnosed anxiety the trials point one way, and the scale makes the size clear. The Hamilton Anxiety Rating Scale runs from 0 to 56, and a change of 4 to 5 points is usually regarded as noticeable. In Iran, 40 adults with generalised anxiety disorder on an SSRI added 1 g a day of root extract or placebo for 6 weeks: the ashwagandha group fell 14 points and the placebo group 8, with no adverse effects reported.² Across five trials of 254 people the pooled fall was about 6 points more than placebo, with heterogeneity of 98%: the trials disagreed about the size.³ The wider stress literature agrees on direction, not size: 12 trials of 1,002 people pooled to large effects at low certainty, while a 30-day US trial of 60 stressed adults found every group, placebo included, improved and none differed.^{5, 6} No trial has compared it with a prescribed medicine or therapy as a replacement; two small trials in diagnosed disorders added it to an SSRI: the anxiety trial above and one in 30 people with obsessive-compulsive disorder.^{2, 14} Anyone whose anxiety affects daily life should see a GP; in England NHS talking therapies take self-referrals.⁷ If you take an antidepressant, tell the prescriber before adding it; the medicine questions are on who should not take ashwagandha.

Does ashwagandha increase dopamine or serotonin?

Serotonin: a 2026 meta-analysis of 23 trials and 1,706 people reports a pooled rise in blood serotonin of about 32 ng/mL.⁸ Blood serotonin is not brain serotonin, and what that change means for mood is unknown. Dopamine: no human trial has measured it; the claim that it raises dopamine comes from rodent and cell studies. The one mechanism with a clinical footprint is GABA: the authors of the only published withdrawal case propose that the extract acts on GABA signalling, which would fit the drowsiness people report and the racing heart and insomnia their patient had on stopping; a proposed mechanism is not a clinical result.⁹

How does ashwagandha make you feel?

The trials give averages and the forums the range: on UK forums the commonest report is calmer, "anxiety switched off", sleeping through and more energy, usually noticed within one to three weeks; the next commonest is nothing at all. A smaller group describe the opposite, feeling wired or shaky with palpitations or tremor within 3 to 12 days, and five of six such accounts came from people with thyroid conditions, which fits the one direction the pooled data show for thyroxine: up.⁸ Drowsiness is the commonest trial side effect, so "sofa-glue" tiredness, feeling spaced out and next-day grogginess follow higher doses or late dosing; vivid dreams, stomach upset and loose stools are the other recurring reports. "Why do I feel so good" is usually the trial effect arriving. "Why do I feel weird" is usually drowsiness, the dose or a thyroid interaction; with a racing heart, tremor or breathlessness, stop and see a GP, because those are the thyrotoxicosis reports.

Can ashwagandha cause anxiety?

In some people, yes, in three recognisable patterns. The first is thyroid: ashwagandha raises thyroxine, a 600 mg a day trial in 50 people with subclinical hypothyroidism raised T4 by about a fifth in 8 weeks, and the case reports of thyrotoxicosis that resolved on stopping are on the safety page; anyone with a thyroid condition or on levothyroxine needs their prescriber's agreement first.^{10, 8} The second is timing and dose: taken late or in large doses, a minority sleep worse and feel wired; morning dosing or a lower dose is the fix. The third is stopping. A 20-year-old man who stopped 600 mg a day abruptly developed a racing heart, insomnia and anxiety within days, with normal heart, liver and thyroid tests; the authors proposed a withdrawal effect and allowed that his underlying anxiety may have returned, and forum accounts of panic returning one to two weeks after stopping fit either explanation.⁹ How to stop, and what the rebound reports look like, is on is ashwagandha safe to take daily.

Why do I feel flat, numb or unmotivated on ashwagandha?

The trials measured anxiety, stress and sleep scales and found them lower; they did not measure emotional range, motivation or libido, so they can neither confirm nor rule out blunting. A minority of users, concentrated in one large online community, describe feeling flat, detached, unmotivated or without libido after weeks to months, and some describe it lasting weeks or months after stopping; most accounts resolve, and nobody has counted how many this happens to. There is one published case, the withdrawal report above, and no case series.⁹ So "ashwagandha causes anhedonia" is not established fact, and "that's placebo" is not an answer either. What to do is clear: if you notice flatness, stop. If it persists after a few weeks off, see a GP, because low mood and loss of pleasure have other causes worth a proper look. If you take an antidepressant, involve the prescriber rather than stopping either alone. And a suspected reaction to any supplement can be reported through the MHRA Yellow Card scheme, which is how a signal like this gets counted.¹¹

Frequently asked questions

Is ashwagandha good for brain fog?

Brain fog is a description, not a diagnosis, and no trial has used it as an outcome; the nearest evidence is the pooled memory and attention result above.¹ Fog that persists deserves a GP visit: poor sleep, thyroid problems, low iron or B12 and low mood all produce it, and all have tests. The mushroom people most often ask about for brain fog, lion's mane, has its own trials, in older adults with mild impairment, on what lion's mane is good for; ashwagandha vs lion's mane compares the two, and ginkgo's trials are on what ginkgo biloba is good for.

Does ashwagandha calm the nervous system?

The scale changes are the answer: 6 to 14 Hamilton points in small trials, and a cortisol fall of about 28% against 8% on placebo in the single 64-person trial that the "lowers cortisol by 30%" line comes from.^{2, 12} It is not a sedative medicine and has never been compared with one.

Does ashwagandha help with depression?

One supplier-run 90-day trial gave 70 adults with mild to moderate anxiety and depression 500 mg a day of a standardised root extract with piperine and reported better depression and anxiety ratings than placebo, without effect sizes in the abstract.¹³ Antidepressants and talking therapy are the treatments for depression, nobody should stop a prescribed antidepressant for a supplement, and persistent low mood belongs with a GP.

Will the flatness go away after I stop?

In most forum accounts, yes, over days to weeks; a minority describe months, and nobody has the denominator. If it has not lifted a few weeks after stopping, see a GP.

Sources

1. Zhu X, Zeng Q, Lei Y, et al. Effects of Withania somnifera (L.) Dunal (ashwagandha) on cognitive and physical function in adults: a systematic review and meta-analysis. Frontiers in Pharmacology, 2026. PubMed 42199854.
2. Fuladi S, Emami SA, Mohammadpour AH, et al. Assessment of the efficacy of Withania somnifera root extract in patients with generalized anxiety disorder: a randomized double-blind placebo-controlled trial. Current Reviews in Clinical and Experimental Pharmacology, 2021. Randomised trial, 40 adults on SSRIs, 6 weeks; funding not checked. PubMed 32282308.
3. Fatima K, Malik J, Muskan F, et al. Safety and efficacy of Withania somnifera for anxiety and insomnia: systematic review and meta-analysis. Human Psychopharmacology, 2024. PubMed 39083548.
4. Gopukumar K, Thanawala S, Somepalli V, et al. Efficacy and safety of ashwagandha root extract on cognitive functions in healthy, stressed adults: a randomized, double-blind, placebo-controlled study. Evidence-Based Complementary and Alternative Medicine, 2021. PubMed 34858513.
5. 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. Phytotherapy Research, 2022. PubMed 36017529.
6. Remenapp A, Coyle K, Orange T, et al. Efficacy of Withania somnifera supplementation on adult's cognition and mood. Journal of Ayurveda and Integrative Medicine, 2022. PubMed 34838432.
7. NHS. NHS talking therapies for anxiety and depression: how to refer yourself. nhs.uk/tests-and-treatments/talking-therapies.
8. Fornalik M, Malkiewicz A, Adamczak D, et al. Hormonal modulation with Withania somnifera: systematic review and meta-analysis of randomized-controlled trials. Planta Medica, 2026. PubMed 41740946.
9. Holzman A, Brown AE, Kelley J, et al. Unmasking potential withdrawal effects of ashwagandha: a case report and review. Cureus, 2025. PubMed 40476122.
10. Sharma AK, Basu I, Singh S. Efficacy and safety of ashwagandha root extract in subclinical hypothyroid patients: a double-blind, randomized placebo-controlled trial. Journal of Alternative and Complementary Medicine, 2018. PubMed 28829155.
11. Medicines and Healthcare products Regulatory Agency. Yellow Card: report a suspected side effect or safety concern, including herbal and food supplement products. yellowcard.mhra.gov.uk.
12. 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 Journal of Psychological Medicine, 2012. PubMed 23439798.
13. Majeed M, Nagabhushanam K, Murali A, et al. A standardized Withania somnifera (Linn.) root extract with piperine alleviates the symptoms of anxiety and depression by increasing serotonin levels: a double-blind, randomized, placebo-controlled study. Journal of Integrative and Complementary Medicine, 2024. Supplier-run. PubMed 37878284.
14. Jahanbakhsh SP, et al. Complementary Therapies in Medicine, 2016. Randomised trial, 30 adults with obsessive-compulsive disorder on SSRIs, 6 weeks; funding not checked. PubMed 27515872.