The Science Behind Ashwagandha: What the Research Says About Stress, Energy and Sleep

Last updated: October 2026.

Ashwagandha (Withania somnifera) has gone from a little-known herb in Ayurvedic tradition to one of the most searched supplements in Ireland. It turns up in drops, capsules, gummies and teas, and is often described as an “adaptogen”, a plant traditionally used to help the body cope with everyday stress.

This guide looks at what ashwagandha actually is, what researchers have studied, what the limits of that research are, and the safety points every buyer should know. It is written to help you make an informed choice, not to sell you a miracle.

The short answer

• Ashwagandha is a shrub from the nightshade family, used for centuries in Ayurvedic practice. The root is the part most commonly used in supplements.
• Most human studies are small and short, usually 6 to 12 weeks, and have looked at self-reported stress, sleep quality and cortisol.
• Results are promising in places, but the evidence is not strong enough to make health claims, and products vary widely in quality.
• It is not suitable for everyone: avoid it in pregnancy and breastfeeding, and speak to your GP if you take medication or have a thyroid, liver or autoimmune condition.

What is ashwagandha?

Ashwagandha is a small evergreen shrub native to India, the Middle East and parts of Africa. Its name comes from Sanskrit and loosely translates as “smell of the horse”, a reference both to the earthy smell of the root and to the traditional idea that it gives strength. In Ayurveda it has been used for well over two thousand years as a rasayana, a category of herbs taken to support general vitality.

Modern supplements usually use a standardised extract of the root, sometimes the root and leaf together. The compounds researchers focus on most are called withanolides, a group of naturally occurring steroidal lactones. Different branded extracts are standardised to different withanolide levels, which is one reason studies are hard to compare directly.

What does “adaptogen” mean?

“Adaptogen” is a term coined in the mid-twentieth century to describe plants believed to help the body maintain balance when under physical or mental stress. It is a useful shorthand for a traditional category, but it is not a recognised scientific or regulatory term in the EU. When you see it on labels, read it as a description of tradition rather than a proven effect.

What have human studies looked at?

Most published ashwagandha research involves healthy adults or adults reporting high stress, and compares an extract against a placebo for a few weeks. Here is an honest summary of the main areas.

Stress and cortisol

Several randomised controlled trials have measured perceived stress using questionnaires, and some have measured cortisol, the hormone your body releases in response to stress. A number of these trials reported lower stress scores in the ashwagandha groups than in the placebo groups over 8 weeks. Systematic reviews have described the findings as encouraging but have also pointed out small sample sizes, short durations and the fact that many trials were funded by extract manufacturers.

Sleep

Some trials have looked at sleep quality and time taken to fall asleep, again using questionnaires and sometimes sleep trackers. A 2021 meta-analysis pooled several of these and reported a small overall improvement in sleep measures compared with placebo, with larger effects in people who already had poor sleep. The authors called for larger, longer, independent studies.

Energy, exercise and focus

A smaller group of studies has looked at strength training, endurance and attention tasks. Results are mixed and the trials are mostly very small, so it is too early to draw conclusions.

Area studied	Typical study length	State of the evidence
Perceived stress	6 to 12 weeks	Promising but small trials, often industry funded
Sleep quality	6 to 12 weeks	Small improvements in pooled data; more research needed
Exercise performance	8 weeks	Very small trials, mixed results
Long-term use	Rarely studied	Little data beyond 3 months

Why the evidence is not settled

It is easy to read a headline about a positive trial and assume the question is answered. A few things make ashwagandha research hard to interpret:

• Different extracts. Root-only, root and leaf, and various withanolide standardisations are all called “ashwagandha”, so results from one product do not automatically apply to another.
• Short studies. Very few trials run beyond three months.
• Self-reported outcomes. Stress and sleep questionnaires are useful but are sensitive to the placebo effect.
• Funding. Many trials were sponsored by companies selling branded extracts.

None of this means ashwagandha does nothing. It means the honest position is “interesting, under-researched, not proven”. Food supplements sold in Ireland cannot claim to treat, prevent or cure any condition, and we do not make such claims.

Safety: who should avoid ashwagandha?

Ashwagandha is widely used and generally reported as well tolerated in short-term studies, but it is not risk-free. Food safety authorities in several European countries have reviewed it in recent years, and Denmark has restricted its sale. Rare cases of liver injury have been reported in the medical literature. Do not take ashwagandha, or speak to your GP or pharmacist first, if any of the following apply:

• You are pregnant, trying to conceive or breastfeeding.
• You have a thyroid condition or take thyroid medication.
• You have a liver condition, or notice symptoms such as yellowing of the skin or eyes, dark urine or unusual tiredness while taking it (stop and see your GP).
• You have an autoimmune condition or take immunosuppressants.
• You take sedatives, sleeping tablets, anti-anxiety medication, or medication for blood pressure or blood sugar.
• You are due to have surgery.

Common mild side effects reported in trials include stomach upset, loose stools and drowsiness. If you notice anything unusual, stop taking it.

How is ashwagandha usually taken?

Ashwagandha comes in capsules, powders, gummies and liquid drops. Drops are popular because they are easy to add to water or take under the tongue, and the serving is simple to adjust. Many people take it in the evening with food, but the right timing depends on the product, so always follow the label and never exceed the recommended serving.

Our Ashwagandha Drops 1500mg (€39.95) are made for exactly this kind of simple daily routine. If you are curious about combining it with CBD, read can you take CBD and ashwagandha together first, and see what Irish customers say in our ashwagandha reviews round-up.

How to choose a quality ashwagandha product

• Know the part used. Root extract is the most studied.
• Check the amount per serving. A clear milligram figure per serving matters more than the total in the bottle.
• Look for testing. Third-party lab reports for contaminants such as heavy metals are a good sign.
• Avoid big promises. Products that claim to cure anxiety or insomnia are breaking EU rules and are best avoided.
• Buy from a business you can contact. Irish sellers with a real address and customer service make returns and questions simple.

Ashwagandha alongside healthy habits

No supplement replaces the basics. Regular sleep and wake times, daylight in the morning, movement you enjoy, time with people you like and limiting alcohol all have far stronger evidence for supporting how you feel day to day. If stress is affecting your sleep, work or relationships, talk to your GP; there is effective support available. Our article on CBD and everyday stress and our breathing techniques guide cover practical steps you can start today.

Frequently asked questions

Is ashwagandha legal in Ireland?

Yes, ashwagandha root is sold as a food supplement in Ireland. Some European countries have restricted it, so it is worth keeping an eye on regulatory updates.

How long does ashwagandha take to work?

Most studies ran for 6 to 12 weeks, so effects, where reported, were measured over weeks rather than days. Results vary from person to person.

Can I take ashwagandha every day?

Many people do, but there is little research on use beyond three months. Follow the label and talk to your GP about longer-term use.

Does ashwagandha make you sleepy?

Some people report drowsiness, which is why many take it in the evening. Avoid driving if it affects you.

Can I take ashwagandha with CBD?

Many people use both, but both can interact with medication. Speak to your GP or pharmacist first if you take any regular medicines.

Is ashwagandha safe in pregnancy?

No. Avoid ashwagandha if you are pregnant, trying to conceive or breastfeeding.

Does ashwagandha affect the thyroid?

Some studies have reported changes in thyroid hormone levels. If you have a thyroid condition or take thyroid medication, check with your GP first.

What is the difference between ashwagandha drops and capsules?

Drops allow a flexible serving and can be added to drinks; capsules are convenient and tasteless. The key is the amount of extract per serving.

Disclaimer: CBD is sold as a food supplement. It is not intended to diagnose, treat, cure or prevent any disease and is not a substitute for medical advice. Always consult a healthcare professional before starting a new supplement, especially if you take medication, are pregnant or breastfeeding.