Guide · Updated 10 October 2026

Magnesium, Herbs and Sleep: What Research Shows

Sleep products are heavily marketed, and the claims often run well ahead of the science. This guide summarises what published reviews actually report about common ingredients, and how much weight that evidence can bear. It is general information, not a recommendation to use any of them.

How to read sleep research

A single small study can make headlines, but systematic reviews, which pool all the eligible trials on a question, give a fairer picture. Even then, a review is only as good as the studies inside it. Small numbers of participants, short durations, varied doses and the tendency for positive results to be published more often can all inflate apparent benefits.

In the summaries below, we report what the reviewers found and how they rated the evidence. None of this is advice to take anything. If sleep is a concern, a GP or pharmacist can consider your health, medicines and circumstances, which no article can do.

Magnesium

A 2021 systematic review and meta-analysis looked for trials of oral magnesium for insomnia in older adults. It found only three randomised controlled trials, involving 151 people in total. Pooled results suggested people taking magnesium fell asleep about 17 minutes sooner than those on placebo, while the difference in total sleep time was not statistically significant.

The authors were frank about the limits. All three trials carried a moderate to high risk of bias, and the overall evidence was rated low to very low quality. They concluded that the existing studies were not good enough for doctors to make well-informed recommendations, and that larger, better-designed trials are needed.

Chamomile and passionflower

A 2019 meta-analysis in Phytotherapy Research pooled 12 randomised trials of chamomile across anxiety and sleep outcomes. It reported an improvement in self-rated sleep quality compared with control groups. However, only one trial looked specifically at insomnia, and it found no significant change on a standard insomnia severity scale. The authors called for larger trials.

For passionflower, a 2020 systematic review in Nutrients identified nine clinical trials, but these focused mainly on anxiety rather than sleep. The trials ranged from one to 30 days and used many different measures, which makes comparison difficult. The authors' conclusion was cautious, and good-quality sleep-specific evidence remains thin.

Valerian and lavender

Valerian is one of the most studied herbs for sleep. A 2006 meta-analysis in the American Journal of Medicine found 16 placebo-controlled trials with 1,093 participants. Most had significant methodological problems, and doses and preparations varied widely. A pooled yes-or-no sleep quality measure favoured valerian, but the reviewers found signs of publication bias that may overstate the effect.

Lavender has mostly been studied as an inhaled aroma. A 2012 systematic review identified eight studies, only four of them randomised controlled trials. The reviewers described the evidence as weak, with small samples and design limitations, and said early findings should be viewed with caution until more rigorous trials are done.

Melatonin and its status in Australia

Melatonin is a hormone the body produces as evening approaches, and in Australia it is regulated as a medicine, not sold as a general supplement. Under the Poisons Standard, it is prescription-only (Schedule 4) except for one narrow category: modified-release tablets of 2 mg or less, for adults aged 55 or over, in packs of no more than 30 tablets, which are pharmacist-only (Schedule 3).

That arrangement took effect on 1 June 2021, following a TGA scheduling decision. The Sleep Health Foundation notes that melatonin can cause sleepiness, so it should not be taken before driving or operating machinery, and that long-term use is only appropriate under medical supervision. Healthdirect says a doctor would usually review use after about 3 weeks.

What the research does show

Across these ingredients, the common thread is small, short and inconsistent studies. Some report modest changes on particular measures, but none of the reviews summarised here reached a firm conclusion, and several explicitly called for better trials. Natural does not mean risk-free, either: herbs and supplements can interact with prescription medicines or be unsuitable in pregnancy.

By contrast, Australian health bodies consistently point to cognitive behavioural therapy for insomnia as the leading approach for ongoing sleep difficulty. If you are considering any product for sleep, speak with your GP or pharmacist first, particularly if you take other medicines or have a health condition.

This guide is general information drawn from the sources below. It does not suggest that any product treats a sleep condition. If you are worried about your sleep, see your GP.