Ashwagandha and Sleep: A Critical Analysis of Two Scientific Studies

Ashwagandha (Withania somnifera), also known as “Indian ginseng,” is a plant used for thousands of years in Ayurvedic medicine. In tradition, it is considered an “adaptogen”: a substance that helps the body manage stress, fatigue, and anxiety.

Today it is found in capsules and extracts, which are very popular in the supplement market. One of its most repeated promises is that it helps you sleep better.

To evaluate if this is true, we have reviewed two high-level recent scientific studies, both meta-analyses:

• Kaneez Fatima , Javeria Malik , Fariha Muskan , Ghana Raza , Areesha Waseem, Hiba Shahid, Syeda Fatima Jaffery, Umeed Khan, Muhammad Kashan Zaheer, Yasmeen Shaikh, Ahmed Mustafa Rashid. Systematic review and meta-analysis of randomized controlled trials of Ashwagandha extract for sleep quality and stress. Hum Psychopharmacol. 2024 Nov;39(6):e2911.

  doi: 10.1002/hup.2911.:

  A review of 5 clinical trials with about 400 people, which analyzed not only sleep but also anxiety and stress.

• Kae Ling Cheah, Mohd Noor Norhayati, Lili Husniati Yaacob, Razlina Abdul Rahman. Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis. PLoS One. 2021 Sep 24;16(9):e0257843. doi: 10.1371/journal.pone.0257843:

  A meta-analysis that included 5 clinical trials with 372 people, all focused on sleep.

Let's see what they found, what they have in common, and what their limitations are.

First Meta-analysis (2024): Sleep and Anxiety

This meta-analysis analyzed 5 clinical trials with ≈400 people.

Main Results:

• Better sleep quality compared to placebo (according to questionnaires like the Pittsburgh Sleep Quality Index).

• Reduced time needed to fall asleep.

• Less anxiety, which also contributes to sleeping better.

Subgroups:

• The benefits were clearer in people with diagnosed insomnia, in those who took ≥600 mg daily, and after at least 8 weeks of use.

Study Limitations:

• High statistical heterogeneity (I² = 62%): this means that the studies are not entirely consistent with each other. In some, the results were more positive than in others, which creates some uncertainty.

• Subjective measures: most results were based on questionnaires filled out by the participants themselves. Only one trial used objective tests like polysomnography (the standard in sleep research).

• Funding bias: some trials were funded by manufacturers of Ashwagandha extracts. This does not invalidate the results, but it increases the possibility that the studies are designed or interpreted in a way that is more favorable to the product.

Second Meta-analysis (2021): Effects on Sleep

This meta-analysis focused exclusively on the effect of Ashwagandha on sleep quality.

Methodology:

• It included 5 randomized clinical trials with a total of 372 participants.

• It compared Ashwagandha against a placebo in healthy adults or those with mild to moderate insomnia.

Results:

• Significant improvement in sleep quality.

• A tendency toward a reduction in time to fall asleep.

• Better perception of nocturnal rest in those who took Ashwagandha.

Safety:

• In general, it was well tolerated.

• Mild and temporary adverse effects: digestive discomfort, drowsiness, or occasional headache.

• No serious effects were observed.

Limitations:

• Few studies included.

• Predominance of subjective questionnaires instead of objective measurements.

• Short-term trials (6 to 12 weeks), so we don't know what happens with prolonged use.

Communalities and Differences Between the Two Meta-analyses

Commonalities:

• Ashwagandha may improve sleep quality and reduce the time it takes to fall asleep.

• The effects appear especially with ≥600 mg per day and after several weeks of continuous use.

• Side effects are mild, and no serious problems were reported in the trials.

• The current evidence is promising, but still insufficient.

Differences:

• Focus: Cheah et al. (2021) focused only on sleep, while the 2024 meta-analysis also analyzed anxiety and stress, suggesting that reducing anxiety could be one of the ways Ashwagandha improves rest.

• Safety details: both agree that it is safe in the short term, but the 2024 one insists more on the lack of long-term studies and the need to monitor for possible interactions with medications.

Conclusions for the Reader

In summary, Ashwagandha might help you sleep better, but the available evidence is scarce and preliminary. The studies show:

• Moderate improvements in sleep quality and anxiety.

• Acceptable short-term safety, but insufficient data on prolonged use.

• Lack of solid evidence to recommend it as a standard treatment for insomnia.

In science, when data is limited, the most responsible thing is to acknowledge the uncertainty. Ashwagandha can be seen as a possible complementary aid, but not as a proven treatment for insomnia. If you still want to try Ashwagandha, I have included a link below.

❓ Frequently Asked Questions

1. Does Ashwagandha work for sleep?

   The meta-analyses show moderate, but not conclusive, improvements.

2. What dose has been studied most?

   300–600 mg daily of standardized extract, for 6 to 12 weeks.

3. What does statistical heterogeneity (I² = 62%) mean?

   That the results of the studies are not uniform: some found clear benefits, others less so. This weakens the general conclusion.

4. What is funding bias?

   When a study is funded by the company that manufactures the product, there is a possibility that the results will be presented more favorably, even if the data is correct.

5. Is Ashwagandha safe?

   In the short term, it appears safe, with mild adverse effects. There is not enough data on prolonged use.