The sleep aid with the clearest warning is the drugstore antihistamine

Key takeaways

• The American Geriatrics Society’s 2023 Beers Criteria strongly advise adults 65 and older to avoid diphenhydramine and doxylamine, old antihistamines people take for sleep, partly because tolerance develops when they’re used that way¹³.
• Two analyses of valerian trials found that people often said they slept better, but the 2010 review found no benefit on sleep-rating scales or time to fall asleep³⁴.
• A published pilot study of tart cherry juice for insomnia had 8 participants and was funded by a group backed by cherry growers and processors⁸.
• In a 2017 test of 84 CBD extracts sold online, only 26 contained an amount of CBD within 10% of the label, and 18 contained THC¹¹.
• Ashwagandha has been linked to rare liver injury, and Denmark banned it from supplements in 2023, so check the safety flags before you buy any sleep product⁶⁷.

In 2017, a team led by Jack Losso of Louisiana State University reported a pilot study of tart cherry juice for chronic insomnia⁸. It included eight adults over 50⁸.

For two weeks, they drank 240 milliliters, about a cup, of Montmorency tart cherry juice in the morning and again 1 to 2 hours before bed. For another two weeks, they drank a placebo⁸. Overnight sleep recordings showed their sleep time rose by 84 minutes on the juice, the trade publication NutraIngredients reported⁸. One questionnaire score improved, and the rest showed no significant change⁸.

The Cherry Marketing Institute, a not-for-profit backed by North American tart cherry growers and processors, paid for the work⁸.

None of that makes the result false. A small study can point to something real, and a funder can stay out of the work. But it shows how a sleep claim travels: a tiny pilot, an interested sponsor, then a confident line on a label or a social media post.

The sleep-aid aisle is full of claims built this way. It mixes herbs, amino acids, cannabinoids and decades-old antihistamines. We walk through how to sort them, and why the product with the strongest official warning may be the most familiar one.

Six questions that sort any sleep-aid claim

Use these questions on any bottle, box of tea or online ad. You’ll often need the study itself, not the label, to answer them.

1. What exactly was tested? A cup of tea, a dried root, a standardized extract and a capsule are different doses. Name the form and the amount.
2. In whom? Healthy volunteers, people with diagnosed insomnia and children with ADHD can respond differently.
3. How many people, and for how long? A two-week trial of eight people is a lead. Hundreds of people over months is stronger evidence.
4. How was sleep measured? Questionnaires capture how you feel. Sleep-lab recordings and wrist monitors measure sleep more directly. The two can disagree.
5. Who paid? Look for the funding and conflict-of-interest statements near the end of a paper. Ingredient makers, trade groups and federal agencies all fund sleep research.
6. How big was the effect, and what are the safety flags? “Significant” can mean a few minutes. Then check liver warnings, drug interactions, pregnancy and age.

A product that can’t answer most of these questions hasn’t earned your money yet. Our articles on proprietary blends, supplement stacks, structure/function claims and third-party testing explain how to read the label itself.

Valerian: years of trials, still no clear answer

Valerian is the classic sleep herb. Its roots and underground stems are the parts used as medicine², and trials have tested both extracts and dried root³.

In 2006, Stephen Bent and colleagues pooled 16 placebo-controlled trials with 1,093 people³. In six studies that simply asked whether sleep improved, people taking valerian were about 1.8 times as likely to say yes³.

The authors flagged problems. They found signs of publication bias, meaning studies with disappointing results may never have been published³. Daily doses ranged from 225 to 1,215 milligrams, and only 2 of the 16 studies said their extract was standardized³. Their review was funded by a grant from NIH’s complementary medicine center, not by an herb company³.

A 2010 review of 18 trials in the journal Sleep Medicine found a smaller edge on the same yes-or-no question⁴. But on sleep-quality scales and time to fall asleep, valerian and placebo came out the same, with a difference of less than a minute in sleep onset⁴.

NCCIH, the National Center for Complementary and Integrative Health, calls the evidence inconsistent². In 2017, the American Academy of Sleep Medicine (AASM) issued a weak recommendation against valerian for chronic insomnia⁵.

Safety is mostly reassuring for short-term use. Side effects include headache, stomach upset and vivid dreams². NCCIH reports very rare liver injury, most often when valerian was combined with other herbs, and withdrawal-type symptoms if people stop suddenly after long use². Don’t combine it with alcohol or sedatives².

Ashwagandha and L-theanine: small trials, branded ingredients

Ashwagandha has a history in Ayurveda, India’s traditional medicine, that stretches back thousands of years⁶. NCCIH says some ashwagandha preparations may help insomnia and stress, but many trials are small and tested different preparations⁶. Its summary doesn’t say who funded them, so check each study’s funding note.

Safety needs attention. NCCIH reports a number of cases linking ashwagandha supplements to liver injury⁶. It advises against ashwagandha in pregnancy and while breastfeeding, for people with thyroid or autoimmune disorders, before surgery, and for people with hormone-sensitive prostate cancer⁶. It may interact with diabetes, blood pressure, thyroid, seizure and immune-suppressing medicines and with sedatives⁶.

Europe has moved faster. A Danish university report in 2020 found too little evidence to set a safe intake level, and Denmark then banned ashwagandha from food supplements in 2023, according to the trade publication NutraIngredients⁷. Dutch health authorities advised against using it in 2024, Britain’s Food Standards Agency asked for evidence the same year, and as of July 2026, EU regulators were still weighing a formal review⁷.

L-theanine is an amino acid sold as a supplement. In a 2019 trial published in the journal Nutrients, 30 healthy adults took 200 milligrams a day for four weeks and a placebo for four weeks, in random order⁹. On L-theanine, their questionnaire scores for trouble falling asleep, sleep disturbance and use of sleep medicine improved compared with placebo⁹.

Two of the seven authors listed email addresses at Taiyo Kagaku, a Japanese company, and the journal page we could open didn’t show the paper’s funding statement⁹. That’s a promising lead from a small, company-linked trial, not a settled answer. Glycine, another amino acid sold for sleep, has a similar backstory; our magnesium article in this series covers it.

CBD and kava: legal gray zones and liver warnings

CBD, or cannabidiol, is a compound from the cannabis plant. The FDA has approved exactly one CBD drug, Epidiolex, for rare seizure disorders, and none for sleep¹⁰. On its CBD questions-and-answers page, last revised in July 2024, the agency says CBD is excluded from the legal definition of a dietary supplement and can’t be added to foods sold across state lines¹⁰. That page is the place to check for any later change.

For sleep, a 2020 review of 12 studies with 250 people found too little evidence to support cannabinoids for any sleep disorder¹. NCCIH is still funding research on CBD and sleep in people with multiple sclerosis and chronic pain¹.

NCCIH links CBD to liver injury, interactions with other drugs and harm to the male reproductive system¹. And the label may be wrong.

In a 2017 study in JAMA, researchers bought 84 CBD extracts from 31 companies online¹¹. Only 26 had CBD within 10% of the label. Thirty-six had more, 22 had less, and 18 contained THC, the compound that causes a high¹¹.

That study was funded by a nonprofit cannabinoid research institute that, the authors said, had no part in the design, and two authors reported fees from cannabis, hemp and drug companies¹¹. Industry ties cut both ways: here, people connected to the business documented its labeling problems.

Kava comes from a pepper-family plant that Pacific Islanders have used in ceremonial drinks for thousands of years¹². There’s very little research on kava for insomnia¹.

Kava has been tied to rare cases of serious liver damage, including deaths¹¹². Early cases involved alcohol or acetone extracts, but some involved water-prepared drinks¹². Never mix kava with alcohol or sedative drugs, and NCCIH notes special risks in pregnancy and breastfeeding¹².

The drugstore sleep aid carries the clearest warning

Diphenhydramine, the antihistamine sold without a prescription as Benadryl, is also taken for sleep, and the AASM’s insomnia guideline addresses it directly⁵¹⁴. Doxylamine is a close cousin. The Beers Criteria list both among the first-generation antihistamines and note that tolerance builds when people take them as sleep aids¹³. If you use a nighttime or “PM” product, look for either name among the active ingredients on the label.

These are regulated over-the-counter drugs, not supplements. Yet they draw the firmest warnings in this article. In 2017, the AASM issued a weak recommendation against diphenhydramine for chronic insomnia, the same rating it gave valerian and melatonin⁵.

For older adults, the American Geriatrics Society goes further. Its 2023 Beers Criteria, a list of medicines that are often a poor choice for people 65 and older, say to avoid first-generation antihistamines, including diphenhydramine and doxylamine¹³. That advice is rated strong, based on moderate-quality evidence¹³.

The reasons: these drugs are highly anticholinergic¹³. That means they block acetylcholine, a chemical messenger the brain and body rely on. Older bodies clear them more slowly, and tolerance develops when people take them for sleep¹³. The same list says to keep anticholinergic drugs to a minimum, because taking more than one raises the risk of mental decline, delirium and falls¹³.

A long-term study added a worrying signal. In 2015, Shelly Gray of the University of Washington and colleagues followed nearly 3,500 older adults in the Adult Changes in Thought study for more than seven years¹⁴. People who used more strong anticholinergic drugs, or used them longer, had a higher risk of dementia, and the risk may persist after stopping¹⁴. The study was funded by the National Institute on Aging¹⁴.

This kind of study tracks people over time, so it shows a link, not proof of cause. The researchers advised older adults to tell their clinicians about all over-the-counter use and not to stop any medicine without talking to them first¹⁴.

The same Beers list also says older adults should avoid prescription “Z-drug” sleeping pills such as zolpidem, citing side effects similar to benzodiazepine sedatives and little gain in sleep¹³. Skepticism applies to every shelf.

The scorecard, applied to five products

Product	What was tested, in whom	Who paid	Effect	Safety flags	Rating
Valerian root	225–1,215 mg/day extracts or dried root, trials of a month or less3	2006 review: federal grant; trial funding not reported3	People more often said they slept better; no change on rating scales or sleep onset34	Rare liver injury; withdrawal; no alcohol or sedatives2	Not enough evidence of a real benefit
Ashwagandha	Varied preparations, mostly small trials6	Not stated in NCCIH’s summary6	May help insomnia and stress6	Liver injury cases; pregnancy, thyroid, autoimmune, prostate cancer; banned in Denmark67	Promising but early
CBD oil	Cannabinoids; a 2020 review found 12 studies with 250 people in all1	Varies by study	Too little evidence for any sleep disorder1	Liver injury, drug interactions; labels often wrong111	Not enough evidence
Tart cherry juice	About a cup twice daily for 2 weeks, 8 adults over 50 with insomnia8	Cherry growers’ marketing group8	Sleep time up 84 minutes on juice; most questionnaire scores unchanged8	Lead author reported no adverse events, but the pilot was tiny8	Not enough evidence
Diphenhydramine or doxylamine	Old antihistamines taken for sleep513	Not applicable	AASM advises against for chronic insomnia5	Avoid in older adults; tolerance; dementia link in long-term study1314	Evidence says no, or unsafe for older adults

Tradition, purity and the cup of tea

Many readers come to sleep herbs through tradition, such as ashwagandha in Ayurveda or kava in Pacific ceremony⁶¹². Long use deserves respect. But a capsule of concentrated extract isn’t the same thing as a traditional drink.

The clearest warning about “natural” sleep aids came from a manufacturing failure. In 1989, L-tryptophan supplements were pulled after an outbreak of eosinophilia-myalgia syndrome, a rare illness that can leave people badly disabled or kill them¹. Investigators tied the outbreak to tainted, lab-made L-tryptophan from one manufacturer¹.

The outbreak came from contamination, not from the amino acid itself. Still, NCCIH warns that L-tryptophan can cause life-threatening serotonin toxicity when combined with some medicines, and the AASM advises against it for chronic insomnia¹⁵.

That’s the case for asking who makes your product and who checks it. NCCIH warns that the word “standardized” doesn’t guarantee quality or consistency¹.

Bedtime teas belong in this conversation too. A warm, caffeine-free cup can be a pleasant signal to slow down.

But valerian trials tested 225 to 1,215 milligrams a day of extract or dried root³. A tea box that doesn’t list grams of each herb per bag gives you no way to compare. Our herbal tea guide shows how to weigh a bag and judge a blend, and our chamomile article in this series covers the most popular bedtime tea.

Where sleep aids fit, and when to get help

None of these products is the first-line treatment for chronic insomnia. NCCIH notes that cognitive behavioral therapy for insomnia, or CBT-I, is the most strongly recommended treatment¹. It’s a short, structured program that changes sleep habits and the worries that keep you awake, and our insomnia guide in this series explains how to find it.

Tell every clinician and pharmacist what you take for sleep, including teas and gummies. NCCIH advises extra care when combining prescription, over-the-counter and supplement sleep products¹. Pregnant or nursing people, and parents thinking about any sleep product for a child, should ask a clinician first¹.

MedlinePlus, from the National Library of Medicine, lists signs of a possible sleep disorder that call for a checkup¹⁵:

• You regularly take more than 30 minutes to fall asleep¹⁵.
• You often wake several times and struggle to fall back asleep, or wake too early¹⁵.
• You’re often sleepy during the day or fall asleep at the wrong times¹⁵.
• Your bed partner notices loud snoring, gasping, choking or pauses in breathing¹⁵.
• You feel creeping or tingling in your legs that eases when you move them¹⁵.

MedlinePlus also advises checking with your provider before you take any medicine or supplement¹⁵. Report problems with a supplement to the FDA’s Safety Reporting Portal at safetyreporting.hhs.gov and misleading claims to the FTC at ReportFraud.ftc.gov. For a child who swallowed a sleep product, call Poison Control at 1-800-222-1222.

Questions readers ask

The bottom line

The sleep-aid aisle rewards a skeptical shopper. Valerian has many mixed trials, ashwagandha and L-theanine rest on small studies, CBD and tart cherry juice have little sleep evidence, and kava and ashwagandha carry liver warnings.

The most familiar product, the drugstore antihistamine, carries the clearest warning for older adults. Use the six questions on every claim, tell your clinicians what you take, and treat chronic insomnia with CBT-I first.

Related reading

• The supplement facts panel and the blend that hides your dose
• Why supplement labels say ‘supports’ and never say ‘cures’
• Third-party tested says what’s in the bottle, not that it works
• How to judge a cup of herbal tea, which is gentle but not automatically harmless
• A stack of safe supplements can add up to an unsafe dose

Sources

1. National Center for Complementary and Integrative Health. “Sleep Disorders and Complementary Health Approaches.” NIH, last updated May 2024. nccih.nih.gov
2. National Center for Complementary and Integrative Health. “Valerian.” NIH, last updated May 2025. nccih.nih.gov
3. Bent S, Padula A, Moore D, Patterson M, Mehling W. “Valerian for Sleep: A Systematic Review and Meta-Analysis.” American Journal of Medicine, 2006;119(12):1005–1012. Abstract: em-consulte.com ; full text: e-lactancia.org
4. Fernández-San-Martín MI, et al. “Effectiveness of Valerian on Insomnia: A Meta-Analysis of Randomized Placebo-Controlled Trials.” Sleep Medicine, 2010 (abstract via QxMD). qxmd.com
5. American Academy of Sleep Medicine. “Pharmacologic Treatment of Chronic Insomnia in Adults: Guideline at a Glance” (Sateia MJ et al., Journal of Clinical Sleep Medicine, 2017;13(2):307–349). AASM. aasm.org
6. National Center for Complementary and Integrative Health. “Ashwagandha.” NIH, last updated March 2023. nccih.nih.gov
7. Hancocks N. “Timeline: Will Authorities De-throne the King of Herbs?” NutraIngredients, July 6, 2026. nutraingredients.com
8. NutraIngredients. “Tart Cherry Juice May Help You Get a Good Night’s Sleep: Study” (on Losso JN, Greenway FL, et al., American Journal of Therapeutics). November 2, 2017. nutraingredients.com
9. Hidese S, Ogawa S, Ota M, Ishida I, Yasukawa Z, Ozeki M, Kunugi H. “Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial.” Nutrients, 2019;11(10):2362 (journal review-report page). pubmed.ncbi.nlm.nih.gov
10. U.S. Food and Drug Administration. “FDA Regulation of Cannabis and Cannabis-Derived Products, Including Cannabidiol (CBD).” Content current as of July 16, 2024. fda.gov
11. Bonn-Miller MO, Loflin MJE, Thomas BF, Marcu JP, Hyke T, Vandrey R. “Labeling Accuracy of Cannabidiol Extracts Sold Online.” JAMA, 2017;318(17):1708–1709. pubmed.ncbi.nlm.nih.gov
12. National Center for Complementary and Integrative Health. “Kava.” NIH, last updated April 2025. nccih.nih.gov
13. American Geriatrics Society. “2023 AGS Beers Criteria for Potentially Inappropriate Medication Use in Older Adults” (pocket card; Journal of the American Geriatrics Society, 2023). gwep.usc.edu
14. Kaiser Permanente Washington Health Research Institute. “Higher Dementia Risk Linked to More Use of Common Drugs” (on Gray SL, et al., JAMA Internal Medicine, 2015). January 26, 2015. kpwashingtonresearch.org
15. MedlinePlus. “Sleep Disorders.” National Library of Medicine, updated December 4, 2025. medlineplus.gov