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As a biotechnologist, I read supplement labels the way I used to read lab protocols: what's the dose, who was tested, and how big was the effect? As someone working 12-hour rotating shifts, I also know the 3am temptation to buy whatever promises to knock you out after a night shift. So I went looking for the best supplements for sleep and scored each one on the human trials, not the marketing.
Short version: a few have modest evidence, one is prescription-only in Australia, and the free option beats all of them.
General information, not medical advice. If poor sleep has lasted more than a few weeks, or you snore loudly or wake up gasping, see your GP. Ongoing insomnia and sleep apnoea are worth a proper assessment.
Why the best supplements for sleep still give small results
Most sleep supplements are tested in small groups, for a few weeks, often in older adults or people who already sleep well. Effects are usually measured in minutes: how much faster you fall asleep (sleep onset latency) or how much longer you stay asleep (total sleep time). Keep that in mind. A supplement that gets you to sleep 10 minutes faster is a real result, but it won't fix a body clock that's on the wrong roster.
Here's my scorecard, from strongest to weakest evidence for an ordinary adult.
1. Magnesium: modest evidence, cheap, low risk for most
Score: 3 / 5
A 2021 systematic review pooled three small randomised trials in 151 older adults with insomnia. People taking magnesium fell asleep about 17 minutes faster than placebo. Total sleep time went up by about 16 minutes, but that result wasn't statistically significant, and the authors rated the evidence low to very low quality (Mah & Pitre, 2021).
A newer trial is more useful for working-age adults. In 2025, German researchers gave 155 adults aged 18 to 65 who reported poor sleep either 250 mg of elemental magnesium as bisglycinate or a placebo for 4 weeks. Insomnia scores improved a little more with magnesium, but the effect size was small. Interestingly, people who ate the least magnesium in their usual diet seemed to benefit most (Schuster et al., 2025).
What that means: if your diet is low in magnesium (not many nuts, seeds, legumes, leafy greens or wholegrains), a supplement may help a little. If you already eat well, expect little. I covered the food-first side in magnesium glycinate vs food. If you want to try one, glycinate or bisglycinate forms are the ones used in the newer trial and tend to be gentler on the gut (magnesium glycinate options on Amazon AU).
Cautions: high doses can cause loose stools. Check with your doctor or pharmacist first if you have kidney disease or take antibiotics, osteoporosis medicines or other prescription drugs, because magnesium can interfere with absorption.
2. Glycine: interesting, small and industry-funded
Score: 2 / 5
Glycine is a simple amino acid your body makes and you also get from protein foods (gelatine and collagen-rich cuts are high in it). Japanese researchers found that 3 g before bed improved how people felt the next day. In one trial, healthy volunteers had their sleep cut by 25% for three nights. Those given glycine reported less fatigue and did better on a reaction-time test than with placebo (Bannai et al., 2012).
The fine print: the trials are small, short and run by researchers at a company that makes glycine. That doesn't make them wrong, but it's exactly the kind of evidence I want to see replicated independently before calling it proven. If you're curious, it's a low-cost experiment (glycine powder on Amazon AU), but it's not a fix for shift-work sleep.
3. Tart cherry: one tiny trial and a lot of hype
Score: 1.5 / 5
Montmorency tart cherries contain small amounts of melatonin. In a crossover trial, 20 healthy adults drank tart cherry juice concentrate or a placebo for 7 days. Melatonin levels in their urine rose, and their watch-measured sleep time and sleep efficiency improved (Howatson et al., 2012).
Twenty people for one week is a pilot study, not proof. Juice concentrates also carry a fair bit of natural sugar. If you like it, have it as food. I wouldn't build a plan around it.
4. Melatonin: prescription-only in Australia, and it's not a sleeping pill
Score: 2.5 / 5 for shift workers, with a doctor
Melatonin is the hormone your brain releases when it gets dark. It's a timing signal, not a sedative. In Australia it's regulated as a medicine: you need a prescription, except for modified-release 2 mg tablets that a pharmacist can supply to adults aged 55 and over (TGA scheduling decision). The overseas gummies you see online aren't the same thing, and their labelled doses aren't always reliable.
For shift workers specifically, the best summary is a Cochrane review of 15 trials. Melatonin taken after a night shift may add about 24 minutes of daytime sleep, but it didn't help people fall asleep faster, and the evidence was rated low quality (Liira et al., 2014).
What that means: melatonin may have a place for some shift workers, but timing matters and the wrong timing can shift your body clock the wrong way. That's a conversation for your GP, not a purchase from an overseas website.
5. The free option that beats all of them
Score: 5 / 5
None of the supplements above comes close to what a consistent sleep routine does. Here's what I use on my own roster:
- Protect an anchor block. Keep roughly 4 hours of sleep at the same time every day, workdays and days off. I explained the research behind this in waking up tired after night shift.
- Make the room dark and cool. Blackout curtains or a good eye mask matter more after a night shift than any capsule, because daylight tells your brain it's morning (contoured sleep masks on Amazon AU).
- Set a caffeine cut-off. Caffeine stays in your system for hours. Decide your last-coffee time based on when you plan to sleep, not on when you feel tired.
- Keep the last meal small. A light, protein-based snack is easier to sleep on than a big, greasy meal.
- Use naps on purpose. A short, planned nap before a night shift helps alertness. More on that in pre-shift naps.
The scorecard in one place
- Consistent sleep window, dark room, caffeine cut-off: 5 / 5, free
- Magnesium (glycinate/bisglycinate): 3 / 5, small benefit, most likely if your diet is low in magnesium
- Melatonin: 2.5 / 5 for shift workers, prescription-only in Australia (pharmacist for 55+)
- Glycine: 2 / 5, promising but small, industry-funded trials
- Tart cherry: 1.5 / 5, one tiny trial
The honest limitations
Every study here is small or short, and most measured sleep with questionnaires rather than sleep-lab recordings. Few trials included shift workers, and none of them tested people on rotating 12-hour rosters like mine. Supplements also vary in quality and dose between brands. None of these products treats insomnia or any sleep disorder. At best, they nudge sleep by minutes.
Your next step
Before you buy another bottle, sort out the basics: anchor block, dark room, caffeine cut-off. Then, if you still want to try something, magnesium is the most reasonable first experiment for most adults.
Want to know how your body type affects the way you handle food, training and recovery? Grab my free Biotype Guide. It takes about 10 minutes and gives you a starting point built around your biology.
Sources
- Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults: a systematic review & meta-analysis. BMC Complement Med Ther. 2021;21:125. doi:10.1186/s12906-021-03297-z (correction: doi:10.1186/s12906-024-04721-w)
- Schuster J, Cycelskij I, Lopresti A, Hahn A. Magnesium bisglycinate supplementation in healthy adults reporting poor sleep: a randomized, placebo-controlled trial. Nat Sci Sleep. 2025;17:2027–2040. doi:10.2147/NSS.S524348
- Bannai M, Kawai N, Ono K, et al. The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. Front Neurol. 2012;3:61. doi:10.3389/fneur.2012.00061
- Howatson G, Bell PG, Tallent J, et al. Effect of tart cherry juice (Prunus cerasus) on melatonin levels and enhanced sleep quality. Eur J Nutr. 2012;51(8):909–916. doi:10.1007/s00394-011-0263-7
- Liira J, Verbeek JH, Costa G, et al. Pharmacological interventions for sleepiness and sleep disturbances caused by shift work. Cochrane Database Syst Rev. 2014;(8):CD009776. doi:10.1002/14651858.CD009776.pub2
- Therapeutic Goods Administration. Notice of final decision to amend the Poisons Standard in relation to melatonin. tga.gov.au
