EVIDENCE

Which supplements help you sleep? What the research shows

Magnesium, L-theanine, melatonin, saffron, glycine and tart cherry: what the trials found, the doses studied, and when poor sleep is a reason to see a doctor instead.

The short version

Sleep habits come first: adults need 7 or more hours, and the CDC suggests a fixed schedule, a cool dark room, no screens for 30 minutes before bed and no caffeine in the afternoon or evening.
The supplement evidence is modest and mostly from small trials. Magnesium, L-theanine (200 mg) and saffron extract (28 mg a day) have small randomized trials showing better sleep scores.
Melatonin is best studied for timing problems such as jet lag. Low doses (0.3 mg) have been studied, and there isn't enough strong evidence to recommend it for long-term insomnia.
Glycine (3 g before bed) and tart cherry have early, small studies only.
Loud snoring, gasping or pauses in breathing, or an urge to move your legs at night are reasons to see a doctor; the last may call for a ferritin test.

What should you try before sleep supplements?

Start with sleep habits, because no supplement makes up for too little time in bed. The CDC recommends 7 or more hours a night for adults aged 18 to 60, and 7 to 9 hours for ages 61 to 64.

Go to bed and get up at the same time every day, including weekends.
Keep the bedroom quiet, relaxing and cool.
Turn off electronic devices at least 30 minutes before bed.
Avoid large meals and alcohol before bedtime.
Avoid caffeine in the afternoon and evening.
Exercise regularly.

For long-running insomnia, NCCIH notes that the American College of Physicians recommends cognitive behavioral therapy for insomnia (CBT-I) as the first approach.

Does magnesium help you sleep?

Possibly a little, but the evidence is thin. A 2021 systematic review found only 3 randomized trials of magnesium for sleep in older adults, with 151 people in total.

Pooled together, people taking magnesium fell asleep about 17 minutes faster than with placebo. Total sleep time rose by about 16 minutes, but that difference was not statistically significant, and the reviewers rated the evidence low to very low quality.

In one of those trials, 46 older adults with insomnia took 500 mg of magnesium or placebo daily for 8 weeks. The magnesium group reported better insomnia severity scores, sleep efficiency and time to fall asleep. The trials were small and in older adults, so the results may not apply to everyone.

Does L-theanine help with sleep?

Early research suggests L-theanine, an amino acid found in tea, may support sleep quality, especially when stress is part of the problem.

In a 2019 randomized, placebo-controlled crossover trial, 30 healthy adults took 200 mg of L-theanine a day for 4 weeks. Their overall sleep quality scores improved, including time to fall asleep and sleep disturbance, and stress-related symptoms eased compared with placebo. It was a small study, so larger trials are needed.

Melatonin: what dose, when, and for how long?

Melatonin is a hormone that signals night to your body clock, so it is best suited to timing problems, not as an all-purpose sleeping pill.

What it is studied for: NCCIH says research suggests melatonin may help with jet lag, but there isn't enough strong evidence to recommend it for chronic insomnia.
Dose: low doses have been studied. In a trial in adults over 50 with insomnia, 0.3 mg taken 30 minutes before bed restored sleep efficiency, while 3 mg kept blood melatonin raised into the daytime and lowered body temperature.
Timing: trials typically give it 30 minutes to 1 hour before the desired bedtime.
Duration: NCCIH says short-term use appears safe for most people, but information on long-term safety is lacking. Talk with a doctor before using it for months.
Who should ask first: people with epilepsy, anyone taking blood thinners, and parents considering it for children.
Label accuracy: in a 2023 study, 22 of 25 melatonin gummies were inaccurately labeled.

If your Apiece blend includes melatonin, the exact amount is listed with every other ingredient.

What about saffron, glycine and tart cherry?

Each has a few small studies with encouraging results, but none is well established.

Saffron: in a 28-day randomized trial, 63 adults aged 18 to 70 with self-reported poor sleep took a standardized saffron extract (14 mg twice daily) or placebo. Saffron improved insomnia severity and sleep quality ratings.
Saffron was well tolerated, with no reported adverse effects, though the study was small and funded by the extract's maker.
Glycine: this amino acid has been studied at 3 g before bed. In sleep-restricted healthy volunteers, it reduced next-day fatigue and showed a trend toward less sleepiness. Earlier work by the same group reported better sleep quality.
Tart cherry: in a 7-day crossover trial of 20 adults, tart cherry juice concentrate raised melatonin levels and increased total sleep time and sleep efficiency. Most research used juice, so it is not known whether capsule extracts work the same way.

When is poor sleep a reason to see a doctor?

See a doctor if sleep problems are regular, or if you have signs of a sleep disorder that a supplement won't address.

Possible sleep apnea: loud, frequent snoring, breathing that stops and starts, gasping for air, daytime sleepiness, dry mouth, headaches or waking often to urinate (NHLBI).
Possible restless legs: an urge to move your legs that gets worse in the evening or at rest. The American Academy of Sleep Medicine advises checking ferritin and transferrin saturation, ideally in the morning without iron supplements for 24 hours beforehand.
Iron for restless legs is guided by those results: guidelines suggest supplementing adults when ferritin is at or below 75 ng/mL or transferrin saturation is below 20%. Don't start iron without testing.
Sleep problems that started with a new medicine, during pregnancy, or alongside low mood or anxiety.

The same guideline notes that alcohol, caffeine, some antihistamines and some mood medicines can worsen restless legs, so bring your full medicine and supplement list.

How do you choose and combine sleep supplements safely?

Pick one change at a time, use doses that match the studies, and give it a few weeks; most of these trials ran between 1 and 8 weeks.

Check your totals across products, since many sleep blends add magnesium on top of a multivitamin. Ask your pharmacist before combining sleep supplements with prescription sleep aids, sedating medicines or alcohol. Apiece lists every ingredient and amount in your blend, so it is easy to show your doctor or pharmacist exactly what you take.

Questions

What is the best supplement for sleep?

There is no single best one. Magnesium, L-theanine and saffron extract each have small randomized trials showing modest improvements in sleep scores, and melatonin is best supported for body-clock problems such as jet lag. Sleep habits and, for long-term insomnia, CBT-I come first.

How much melatonin should I take?

Low doses have been studied. In adults over 50 with insomnia, 0.3 mg taken 30 minutes before bed restored sleep efficiency, while 3 mg kept melatonin raised into the next day. Many products contain more. Ask your doctor before using melatonin long term, and before giving it to children.

Is it safe to take melatonin every night?

NCCIH says short-term use appears safe for most people, but information on long-term safety is lacking. If you find you need it every night for weeks, talk with your doctor about what is behind the sleep problem.

Can low iron cause restless legs at night?

Low iron stores are linked to restless legs. The American Academy of Sleep Medicine advises checking ferritin and transferrin saturation, and suggests iron for adults when ferritin is at or below 75 ng/mL or saturation is below 20%. Get tested before taking iron.

Does magnesium glycinate help you sleep?

Magnesium in general has limited evidence for sleep: a review of 3 trials in older adults found people fell asleep about 17 minutes faster, but the evidence quality was low. No large trials have compared magnesium forms, including glycinate, for sleep.

Sources

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*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This page is general information, not medical advice. Check with your doctor or pharmacist before starting a supplement, especially if you take medication, are pregnant or nursing, or have a health condition. Updated 2026-10-20.