Best Supplements for Sleep, According to the Evidence

No supplement has strong evidence for long-term insomnia. Melatonin has the best evidence, but mainly for jet lag, not chronic insomnia. Magnesium and L-theanine have small, early studies with modest effects. Valerian, chamomile and tryptophan haven't been shown to work, kava carries a risk of serious liver damage, and cognitive behavioural therapy for insomnia (CBT-I) is the most strongly recommended treatment.

Sleep supplements are a big market, and the labels promise a lot. Below is what health agencies and the published reviews actually found for each one, how strong that evidence is and who should check with a doctor first.

Which sleep supplements actually work?

A few have some evidence, none has strong evidence for chronic insomnia. Here is a summary:

Supplement	What the evidence shows	Safety notes
Melatonin	May help jet lag. Not enough strong evidence for chronic insomnia^[1].	Appears safe short-term; long-term safety unknown^[1].
Magnesium	Small, low-quality studies: people fell asleep a bit faster^[2].	Supplement upper limit 350 mg a day for adults^[3].
L-theanine	Small improvements in self-rated sleep in a 2025 meta-analysis^[4].	Few studies of L-theanine on its own^[4].
Ashwagandha	Some preparations may help insomnia and stress^[5].	Rare liver injury; avoid in pregnancy^[5].
Valerian	Inconsistent results^[6].	Generally safe short-term^[6].
Chamomile	No conclusive evidence^[7].	Ask your pharmacist if you take medicines.
L-tryptophan	Recommended against for chronic insomnia^[7].	Serotonin toxicity risk with some medicines^[7].
Kava	Not recommended.	Linked to serious, sometimes fatal liver injury^[7].

Does melatonin help you sleep?

It may help with jet lag, but there isn't enough strong evidence to recommend it for chronic insomnia. NCCIH says research suggests melatonin may help with jet lag, while studies in shift workers were generally small or inconclusive^[1]. The American Academy of Sleep Medicine's 2017 guideline recommended against melatonin for treating chronic insomnia^[7].

Short-term use appears safe for most people, with mild side effects such as headache, dizziness, nausea and sleepiness; long-term safety hasn't been established^[1]. Two cautions stand out:

Labels can be wrong. A 2023 study found 22 of 25 melatonin gummy products were inaccurately labelled, containing 74% to 347% of the amount stated^[1].
Medicines. People taking medicine should ask their doctor first, and people with epilepsy or on blood thinners need medical supervision^[1]. Melatonin may also stay active longer in older people and cause daytime drowsiness^[1].

There's been little research on melatonin in pregnancy or breastfeeding^[1]. For children, talk to a doctor before giving it. Our melatonin guide has more on forms and timing.

Is magnesium good for sleep?

Possibly, a little, but the evidence is weak. NCCIH says there is very little research on magnesium for insomnia^[7]. A 2021 review pooled three small trials in 151 older adults: people fell asleep about 17 minutes faster with magnesium than placebo, total sleep time didn't change significantly, and the evidence was rated low to very low quality^[2].

A 2025 trial in 155 adults with poor sleep found that 250 mg of magnesium a day as bisglycinate improved insomnia scores slightly more than placebo after four weeks; the authors called the effect small^[8]. If you try magnesium, keep supplemental magnesium within 350 mg a day, the adult upper limit, unless a doctor advises otherwise, and check with your doctor if you have kidney disease^[3]. More in our magnesium guide, and if you're combining them, can I take magnesium and melatonin together.

Does L-theanine help with sleep?

Early evidence suggests small improvements in how people rate their sleep. L-theanine is an amino acid found in tea. A 2025 systematic review and meta-analysis of 19 studies with 897 participants found small but significant improvements in self-reported time to fall asleep, daytime dysfunction and overall sleep quality^[4].

The authors noted that few studies tested "pure" L-theanine on its own, and that the right dose and duration still need work^[4]. Treat it as a promising but unproven option. See our L-theanine guide.

What about ashwagandha for sleep?

Some preparations may help insomnia and stress, but there are safety caveats. NCCIH says research shows some ashwagandha preparations may be effective for insomnia and stress^[5]. It also notes rare cases of liver injury linked to ashwagandha, advises avoiding it in pregnancy and breastfeeding, and says it isn't recommended for people with autoimmune or thyroid disorders; it may also interact with thyroid medicines^[5].

Which sleep supplements don't work?

Valerian: NCCIH says the evidence is inconsistent, and the 2017 sleep medicine guideline advised against it for chronic insomnia in adults^[6].
Chamomile: there's no conclusive evidence from clinical trials that it helps^[7].
L-tryptophan: the same guideline recommended against it for chronic insomnia, and it may cause life-threatening serotonin toxicity with medicines that affect serotonin^[7].
Kava: linked to liver injury that is sometimes serious or even fatal^[7]. Avoid it.

What works better than supplements for sleep?

CBT-I and steady sleep habits. NCCIH calls cognitive behavioural therapy for insomnia the most strongly recommended treatment^[7]. The NHS suggests going to bed only when sleepy, getting up at the same time every day, relaxing for at least an hour before bed, keeping the bedroom dark and quiet, exercising during the day, and avoiding alcohol, tea or coffee in the 6 hours before bed^[9].

See a GP if changing your habits hasn't helped, if you've had trouble sleeping for months, or if it's making daily life hard to cope with^[9]. Persistent poor sleep can have medical causes worth ruling out.

Who should check with a doctor before taking a sleep supplement?

Anyone who is pregnant or breastfeeding^[1][5].
People with epilepsy, on blood thinners, or taking medicines that affect serotonin^[1][7].
People with thyroid, liver or kidney conditions^[3][5].
Parents considering melatonin for a child.

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FAQ

No supplement has strong evidence for chronic insomnia. Melatonin may help with jet lag^[1], and magnesium and L-theanine show small effects in early studies^[2][4]. CBT-I is the most strongly recommended treatment^[7].

Short-term use appears safe for most people, but long-term safety hasn't been established^[1]. If you need it most nights, talk to your doctor about what's behind your sleep problem.

No interaction between them is listed in the sources here, but each has its own cautions: magnesium with kidney disease and some medicines^[3], melatonin with blood thinners and epilepsy^[1]. Ask your pharmacist.

The evidence is inconsistent, and the American Academy of Sleep Medicine advised against valerian for chronic insomnia in adults^[6].

It may be. A 2023 study found most melatonin gummies tested contained between 74% and 347% of the labelled amount^[1]. A product with third-party testing on the label is worth looking for.

Sources

Educational information, not medical advice. Check with your doctor or pharmacist before starting or changing supplements, especially if you take medication, are pregnant or have a health condition.

Best Supplements for Sleep: What the Evidence Says (and What Fails)