Reviewed by:
Dr. Patricia Núñez de Aysa — Medical expert in Longevity, specialist in Rehabilitation and Traumatology without surgery.
Dr. Joel Cuesta Gascón — Medical expert in sports medicine, rehabilitation, and nutrition.
Last updated: May 2026.
In 30 seconds
- Ashwagandha is one of the most studied adaptogens and, unlike many wellness trends, has solid clinical evidence for stress, anxiety, and sleep.
- It primarily works by regulating the hypothalamic-pituitary-adrenal axis and sustained reduction of elevated cortisol.
- The most supported dosage is 600 mg/day of standardized root extract for at least 8 weeks.
- It is not for everyone: pregnancy, lactation, uncontrolled hyperthyroidism, and liver disease are clear contraindications.
- The quality of the extract matters more than the price: look for standardized forms like KSM-66 or Sensoril.
Why adaptogens are everywhere (and why they sometimes disappoint)
Adaptogens are natural extracts that help the body regulate its stress response without causing sedation. In recent years, they have gained significant prominence, largely due to the increase in chronic stress, lack of rest, and the fast-paced lifestyle we live.
Within this group, one stands out above the rest, both in terms of evidence and media presence: ashwagandha. But as with anything that goes viral, it's worth asking: what does science really say, and what is just marketing?
What is ashwagandha and why is it so widely studied?
Ashwagandha (Withania somnifera) is a plant used for thousands of years in Ayurvedic medicine, the traditional medical system originating in India. In that tradition, it is credited with properties to improve vitality, promote rest, and increase resistance to stress.
The interesting thing is that many of these traditional uses have been confirmed in modern clinical trials. Today, it is one of the most studied adaptogens, and it contains active compounds called withanolides, responsible for a large part of its effects on the nervous and endocrine systems.
How it works: scientifically backed mechanisms
1. Regulation of the Hypothalamic-Pituitary-Adrenal (HPA) axis
This is its central mechanism. Ashwagandha acts on the axis that regulates the stress response, reducing the release of cortisol. In clinical trials on adults with chronic stress, its administration lowers cortisol levels and improves symptoms of anxiety and exhaustion.
2. Neurotransmitter modulation
Ashwagandha increases GABAergic activity (the brain's natural "brake") and modulates serotonergic pathways. This explains its effects:
- Anxiolytic
- Mood improvement
- Sleep quality support
- Feeling of calm without sedation
3. Antioxidant and anti-inflammatory effect
Withanolides and other phytochemicals protect against oxidative damage and neuroinflammation. This is one of the mechanisms attributed to its neuroprotective effect and overall well-being improvement.
What ashwagandha is really for: what the evidence says
Stress and anxiety
This is where it has the most scientific backing. Multiple randomized clinical trials show a significant reduction in cortisol levels and improvement in validated stress and anxiety scales after 8-12 weeks of use. A recent systematic review (Albalawi, 2025) confirms the effect on cortisol, although it notes that the impact on the subjective perception of stress is more variable.
Sleep quality
It is not a sedative. But by lowering elevated cortisol and sympathetic activity, it facilitates the transition to sleep and improves its depth. It is especially useful in the "tired but can't sleep" pattern: exhausted body, racing mind.
Thyroid function
Here there are important nuances. Ashwagandha acts on the hypothalamic-pituitary-thyroid axis by stimulating the secretion of T3 and T4 and reducing TSH. In people with subclinical hypothyroidism, a double-blind trial with 600 mg/day for 8 weeks (Sharma 2018) managed to normalize thyroid indices. In people with hyperthyroidism (especially autoimmune type), this same action can be problematic and requires close medical supervision.
Glycemic control in type 2 diabetes
A systematic review (Durg 2020) describes hypoglycemic effects, improved insulin sensitivity, reduced plasma glucose and HbA1c, and improved lipid profile in patients with type 2 diabetes. Mechanisms include increased glucose uptake in peripheral tissues and protection against the characteristic oxidative damage of the disease.
Important: this does not make ashwagandha a substitute for antidiabetic drugs. It can be a useful adjunct under medical supervision.
Quick table: what you're looking for vs. what ashwagandha can offer
| Goal | Does ashwagandha fit? | Level of evidence |
|---|---|---|
| Chronic stress and elevated cortisol | Yes, fits very well | High |
| Mild-moderate anxiety | Yes, with a good profile | High |
| Racing mind at bedtime | Yes, especially with magnesium and 5-HTP | Medium-high |
| Subclinical hypothyroidism | Possible support, with medical follow-up | Medium |
| Type 2 diabetes | Adjuvant, never a substitute | Medium |
| Sports performance and recovery | Yes, for demanding loads | Medium |
| Immediate sedation | Not its profile | — |
When NOT to take ashwagandha: real contraindications
Ashwagandha has a good safety profile in healthy adults, but it is not for everyone. These are the contraindications you should be aware of:
1. Pregnancy and lactation
It is not recommended due to a lack of sufficient studies in these populations. In medicine, when in doubt with sensitive populations, it is best not to expose oneself.
2. Uncontrolled hyperthyroidism
As it stimulates the secretion of thyroid hormones, it can worsen the condition. If you have hyperthyroidism (especially autoimmune type Graves-Basedow), do not take it without medical evaluation. In some cases, it is used with close monitoring and alternating "rest periods."
3. Liver disease
This is the most important contraindication. Cases of hepatotoxicity associated with ashwagandha consumption have been documented, including acute hepatitis, hepatocellular damage, and even acute liver failure, especially in people with pre-existing liver disease. If you have cirrhosis, hepatitis (autoimmune or viral), liver failure, or any known liver alteration, do not take it.
In healthy adults, however, a 12-month safety study with 600 mg/day (Salve 2025) found no significant alterations in liver function tests.
4. Plant allergy
As with any botanical product, allergy is an absolute contraindication.
5. Specific medication
If you are taking immunosuppressants, sedatives, anxiolytics, thyroid hormones, or antidiabetic drugs, consult a professional first. Ashwagandha can interact and modify their effect.
Dosage: how much and how to take ashwagandha
The dose with the most clinical evidence is:
- 600 mg/day of standardized root extract.
- For at least 8 weeks to obtain the documented benefits on cortisol, anxiety, sleep, and other markers.
- It can be taken in a single dose or divided into two.
- Better with food to improve tolerance.
Some studies use higher doses (up to 1,000-1,200 mg), but the standard dose of 600 mg offers the best risk-benefit balance.
Why extract quality matters so much
Not all ashwagandha extracts are the same. There are products that contain crushed root powder without standardization and products that contain standardized extracts with a specific percentage of withanolides. The difference in effect can be enormous.
The extracts with the most clinical support are the standardized or patented ones:
- KSM-66: root extract, standardized to ≥5% withanolides. The most studied.
- Sensoril: root and leaf extract, high in withanolides.
- Shoden: highly concentrated extract, lower doses.
As a consumer, always check the label: if it only says "ashwagandha root powder" without standardization, the effect will be much less predictable than with a standardized extract.
Ashwagandha and other active ingredients: how it combines well
Ashwagandha works very well combined with other active ingredients that cover complementary fronts:
- With magnesium (bisglycinate): one lowers cortisol, the other relaxes muscles and the nervous system. A very useful synergy for stress and poor sleep.
- With 5-HTP: 5-HTP supports serotonin synthesis; ashwagandha modulates its reuptake. An interesting combination for low mood associated with stress.
- With melatonin: useful when there is anticipatory sleep anxiety and difficulty falling asleep. Ashwagandha lowers heart rate; melatonin signals to the brain that it's time to sleep.
This is precisely the logic of Logout: we combine ashwagandha KSM-66 (350 mg), magnesium bisglycinate (100 mg), 5-HTP (50 mg), and melatonin (0.95 mg) in a single formula designed to improve sleep from several angles at once.
Conclusion: trend or substance?
Ashwagandha is trendy, yes. But unlike many wellness trends, it has a real foundation: clinical studies, identified mechanisms of action, well-established doses, and a reasonable safety profile in healthy adults.
It is not a miracle cure and not for everyone. But, when properly indicated and in its standardized form, it is one of the natural active ingredients with the best relationship between evidence and results available today to support chronic stress, mild anxiety, and sleep quality.
If it fits your case, discover Logout, with KSM-66 ashwagandha in an adjusted dose and combined with magnesium, 5-HTP, and melatonin.
And if you have doubts about whether it suits you (especially if you are taking medication or have a thyroid or liver condition), schedule your free medical consultation or write to us on WhatsApp.
Frequently asked questions about ashwagandha
How long does ashwagandha take to work?
Most studies show significant effects after 4-8 weeks of consistent use. Some effects on sleep and feelings of calm may be noticed earlier, but the full impact on cortisol and anxiety takes weeks.
Can ashwagandha be taken every day?
Yes. Safety studies show that continuous use at 600 mg/day for 12 months in healthy adults does not produce significant alterations. Some professionals recommend "rest periods" (e.g., 8 weeks on, 2-4 weeks off), especially if there are thyroid issues.
Does ashwagandha make you sleepy?
Not directly. It is not a sedative. It reduces elevated cortisol and nervous activation, which indirectly facilitates rest. That's why it fits very well with the "tired but can't sleep" pattern.
Better in the morning or at night?
It works at any time, but if your main goal is rest, it's better at night. If you're looking to modulate general daytime stress, divided into two doses works well.
Does ashwagandha raise or lower the thyroid?
It stimulates the production of thyroid hormones (T3, T4) and reduces TSH. This can be beneficial in subclinical hypothyroidism, but problematic in hyperthyroidism. If you have a thyroid condition, do not take it without medical evaluation.
Is it safe to take ashwagandha with antidepressants?
There is potential for interaction with SSRIs and other psychotropic drugs by acting on serotonergic and GABAergic pathways. Do not take it with antidepressants without consulting your doctor.
Does ashwagandha cause weight gain?
No. It does not provide significant calories and has not been associated with weight changes. Some studies even suggest an improvement in metabolic profile.
What is the difference between KSM-66 and other extracts?
KSM-66 is a patented root extract, standardized to ≥5% withanolides, with over 25 published clinical studies. It is the extract with the most scientific backing today. Other extracts may be valid if they are standardized; unstandardized root powders are much less predictable.
Bibliographic references
- Wiciński M, Fajkiel-Madajczyk A, Kurant Z, et al. Can Ashwagandha Benefit the Endocrine System? — A Review. Int J Mol Sci. 2023;24(22):16513.
- Salve J, Kale S, Prajapati BL, et al. Safety of 12-Months Administration of Ashwagandha Standardized Root Extract in Healthy Adults. Phytother Res. 2025.
- Majeed M, Nagabhushanam K, Mundkur L. A standardized Ashwagandha root extract alleviates stress, anxiety, and improves quality of life. Medicine (Baltimore). 2023;102(41):e35521.
- Lopresti AL, Smith SJ, Malvi H, Kodgule R. An investigation into the stress-relieving and pharmacological actions of an ashwagandha extract. Medicine (Baltimore). 2019;98(37):e17186.
- Pandit S, Srivastav AK, Sur TK, et al. Effects of Withania somnifera Extract in Chronically Stressed Adults: A Randomized Controlled Trial. Nutrients. 2024;16(9):1293.
- Speers AB, Cabey KA, Soumyanath A, Wright KM. Effects of Withania somnifera (Ashwagandha) on Stress and Stress-Related Neuropsychiatric Disorders. Curr Neuropharmacol. 2021;19(9):1468-1495.
- Albalawi AA. Dual impact of Ashwagandha: Significant cortisol reduction but no effects on perceived stress — A systematic review and meta-analysis. Nutr Health. 2025;31(4):1395-1408.
- Sharma AK, Basu I, Singh S. Efficacy and Safety of Ashwagandha Root Extract in Subclinical Hypothyroid Patients. J Altern Complement Med. 2018;24(3):243-248.
- Durg S, Bavage S, Shivaram SB. Withania somnifera (Indian ginseng) in diabetes mellitus: A systematic review and meta-analysis. Phytother Res. 2020;34(5):1041-1059.
- Newton HB. Overview of Ayurveda and Ashwagandha: Bioactive Phytochemicals and Potential Applications. Molecules. 2025;30(21):4272.
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