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Does Zinc Help You Sleep? Eight Small Trials, Explained
A 2024 systematic review found eight small randomised trials of zinc and sleep, at 10 to 73.3 mg a day for 4 to 48 weeks: most reported better sleep quality in adults, none found an effect on sleep disorders, and the reviewers concluded there was "no consensus".1 The care-home trial everyone quotes gave melatonin, magnesium and zinc together, so its result cannot be credited to zinc. Zinc has no authorised sleep wording in Great Britain. The UK amounts are 9.5 mg a day for men and 7 mg for women, and the NHS says: "Do not take more than 25mg of zinc supplements a day unless advised to by a doctor."2 It belongs to the Wellgard zinc guide and the Wellgard sleep guide.
What have the trials of zinc and sleep found?
Eight randomised trials, which do not agree: six in adults, one in children, and one in infants reported from two sites. Most adult trials reported better sleep quality, by questionnaire, than the control group; zinc "did not have a significant effect on sleep disorders"; the results in children were "contradictory".1 Participant numbers are as the review tabulated them.
| Trial | Who, and how many | Zinc, and for how long | Sleep quality result (per the review) |
|---|---|---|---|
| Afzali 2022 | 150 older adults | 30 mg a day, 10 weeks | Better than no supplement1 |
| Haddadian-Khouzani 2022 | 75 adults on haemodialysis | 30 mg a day as gluconate, 12 weeks | Better than placebo1 |
| Gholipour Baradari 2018 | 53 intensive-care nurses | 220 mg zinc sulphate every 72 hours, 4 weeks | Quality and time to fall asleep better than placebo1, 3 |
| Jafari 2020 | 57 young women with premenstrual syndrome | 30 mg a day, 12 weeks | No significant change1, 4 |
| Castro-Marrero 2021 | 50 adults with ME/CFS | 10 mg a day with 1 mg melatonin, 16 weeks | No change1, 5 |
| Ranjbar 2013 | 38 adults with major depression, all on an SSRI | 25 mg a day, 12 weeks | No change in sleep duration1, 6 |
| Kim 2014 | 41 children with atopic dermatitis and low hair zinc | 12 mg a day as zinc oxide, 8 weeks | No change in a sleep-disturbance score1, 7 |
| Kordas 2009 | 434 infants in Zanzibar, 277 in Nepal | 10 mg a day, 12 months | No effect in Zanzibar; longer sleep in Nepal1, 8 |
The three positive trials were in people with a reason to be low in zinc or to sleep badly: older adults, people on dialysis, shift-working nurses. Every result is a questionnaire score, not a sleep recording. The 73.3 mg top of the range is a salt weight, 220 mg of zinc sulphate averaged over three days; that 220 mg supplies 50 mg of elemental zinc.3, 9
Why does everyone quote the care-home study?
Because it is the biggest result in the field, and it was not a zinc trial. In 2011, 43 residents of a long-term care facility in Italy, average age 78 and all with primary insomnia, took 5 mg melatonin, 225 mg magnesium and 11.25 mg zinc, or placebo, an hour before bed for 8 weeks. The supplement group's Pittsburgh Sleep Quality Index improved by 6.8 points more than placebo (95% CI 5.4 to 8.3), and total sleep time rose.10 Three ingredients, one result, no way to tell which did the work; the 2024 review did not include it. Melatonin is the ingredient with its own sleep evidence, and the NHS says: "Melatonin is available on prescription only."11 Why is melatonin prescription-only in the UK has its trial numbers.
Can low zinc affect sleep?
Possibly; the evidence is observational. A 2017 review reports that serum zinc varies with the amount of sleep people get, and that zinc by mouth increased the amount and quality of sleep in mice.12 An association cannot say which came first. The NHS names stress, anxiety or depression, noise, alcohol, caffeine, jet lag and shift work among the most common causes of insomnia; no nutrient is on its list.13 Signs of zinc deficiency has the signs and risk groups; the nutrients with a clearer link to sleep, iron through restless legs above all, are on which vitamin deficiency affects sleep.
Which is better for sleep, zinc or magnesium?
Neither has sleep wording in Great Britain, and neither has a trial base that settles it; magnesium's trials have been pooled, zinc's have not.
| Zinc | Magnesium | |
|---|---|---|
| Randomised trials | 8, most under 160 people, one infant trial of 7111 | 3, pooled: 151 older adults with insomnia14 |
| What changed | Sleep quality scores in most adult trials; no effect on sleep disorders; "no consensus"1 | Sleep onset 17.36 minutes sooner than placebo (95% CI 7.44 to 27.27); total sleep 16.06 minutes longer, not significant; low to very low quality14 |
| NHS supplement line | "Do not take more than 25mg of zinc supplements a day unless advised to by a doctor"2 | "Taking high doses of magnesium (more than 400mg) for a short time can cause diarrhoea"2 |
| Nearest authorised wording | Zinc contributes to normal cognitive function | Magnesium contributes to normal psychological function and to normal functioning of the nervous system |
Magnesium has the one pooled result, in minutes, in older adults who often had low intakes: does magnesium help you sleep covers its forms and timing, the vitamins and minerals guide both minerals' UK amounts, and which sleep supplements have evidence behind them every common ingredient in the same units.
How much zinc should I take for sleep?
There is no sleep dose, because no trial has established one. The facts: the UK reference intakes are 9.5 mg a day for men and 7 mg for women, and the NHS supplement line is 25 mg a day unless a doctor advises otherwise, because "Taking high doses of zinc reduces the amount of copper the body can absorb. This can lead to anaemia and weakening of the bones."2 The trials that reported better sleep quality used 30 mg a day, above that line, or 50 mg every third day; the adult trials at 10 and 25 mg a day found no change.1 That describes what was tested, not a reason to take more. Two products containing zinc, a multivitamin and a vitamin C and zinc tablet say, add up: keep the total inside 25 mg. How much zinc a day has the UK amounts by group.
Should you take zinc at night?
No trial has compared morning with night; the care-home trial dosed an hour before bed, the nurses' trial every 72 hours.3, 10 What is known about timing concerns the stomach: zinc on an empty stomach commonly causes nausea, so most people take it with a meal. It needs spacing from some antibiotics, ciprofloxacin among them, and from iron supplements; anyone on a regular medicine asks a pharmacist first. When is the best time to take zinc covers morning or night in full; can you take zinc and magnesium together covers the bedtime pairing.
Which type of zinc is best for sleep?
Untested. The eight trials used zinc gluconate, zinc sulphate, zinc oxide and unspecified zinc; none compared one form with another, and none measured anything that would show a form matters for sleep.1 Any "best form for sleep" answer reasons from absorption, not from sleep trials. The figure to read on any label is the elemental zinc per serving, which the 25 mg line applies to, whichever salt carries it.
When is poor sleep something to see a GP about?
The NHS says to see a GP if changing your sleeping habits has not helped your insomnia, you have had trouble sleeping for months, or your insomnia is affecting your daily life in a way that makes it hard for you to cope; and to check with your doctor before taking anything for your sleep problems.13 Breathing that stops and starts in sleep, restless legs and low mood for more than two weeks each earn an appointment on their own: when to see a GP about sleep has the NHS and NICE wording and the 111 and 999 lines.
Frequently asked questions
Does zinc make you sleepy?
None of the eight trials reported drowsiness; the positive ones measured sleep quality scores over weeks, not a same-night effect.1
Can zinc cause trouble sleeping?
None of the eight trials reported worse sleep on zinc.1 Nausea from a dose on an empty stomach late in the evening is the likeliest way a zinc tablet disturbs a night.
Does ZMA help you sleep?
ZMA is zinc, magnesium and vitamin B6, and no sleep trial has tested it; the care-home result people attach to it included 5 mg of melatonin, prescription-only in the UK.10, 11
Can I take zinc and magnesium together at night?
No human trial has found that the two interfere, and the care-home trial gave them together.10 Each has its own NHS line, 25 mg of zinc and the 400 mg magnesium figure.2
Sources
- Jazinaki MS, et al. Effects of zinc supplementation on sleep quality in humans: a systematic review of randomized controlled trials. Health Science Reports, 2024. PubMed 39377022.
- NHS. Vitamins and minerals: others (zinc and magnesium). nhs.uk.
- Gholipour Baradari A, et al. The effect of zinc supplementation on sleep quality of ICU nurses: a double blinded randomized controlled trial. Workplace Health & Safety, 2018. PubMed 29241421.
- Jafari F, et al. Effect of zinc supplementation on quality of life and sleep quality in young women with premenstrual syndrome: a randomized, double-blind, placebo-controlled trial. Archives of Gynecology and Obstetrics, 2020. PubMed 32514756.
- Castro-Marrero J, et al. Effect of melatonin plus zinc supplementation on fatigue perception in myalgic encephalomyelitis/chronic fatigue syndrome: a randomized, double-blind, placebo-controlled trial. Antioxidants, 2021. PubMed 34201806.
- Ranjbar E, et al. Effects of zinc supplementation in patients with major depression: a randomized clinical trial. Iranian Journal of Psychiatry, 2013. PubMed 24130605.
- Kim JE, et al. Hair zinc levels and the efficacy of oral zinc supplementation in patients with atopic dermatitis. Acta Dermato-Venereologica, 2014. PubMed 24473704.
- Kordas K, et al. The effects of iron and/or zinc supplementation on maternal reports of sleep in infants from Nepal and Zanzibar. Journal of Developmental and Behavioral Pediatrics, 2009. PubMed 19322104.
- Samman S, Roberts DC. The effect of zinc supplements on plasma zinc and copper levels and the reported symptoms in healthy volunteers. Medical Journal of Australia, 1987. PubMed 3547053.
- Rondanelli M, et al. The effect of melatonin, magnesium, and zinc on primary insomnia in long-term care facility residents in Italy: a double-blind, placebo-controlled clinical trial. Journal of the American Geriatrics Society, 2011. PubMed 21226679.
- NHS. About melatonin. nhs.uk.
- Cherasse Y, Urade Y. Dietary zinc acts as a sleep modulator. International Journal of Molecular Sciences, 2017. PubMed 29113075.
- NHS. Insomnia. nhs.uk.
- Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults: a systematic review and meta-analysis. BMC Complementary Medicine and Therapies, 2021. PubMed 33865376.
This article is general information, not medical advice.
