Magnesium good for insomnia? Review of 12 clinical trials finds no clear benefit

Many people reach for magnesium when they cannot sleep. Word spread that taking magnesium before bed eases tension and helps with sleep, making it one of the most popular ingredients in sleep supplements.

The most frequently cited evidence for magnesium's sleep benefits has been a 2021 meta-analysis. It pooled three clinical trials involving 151 older adults with insomnia and found that those who took magnesium fell asleep about 17 minutes faster.

But a new study that gathered all clinical trials testing magnesium alone found inconsistent results and low certainty of evidence for any sleep benefit.

Researchers from Clinical Research Australia and Murdoch University published their findings Aug. 28 in the Journal of Dietary Supplements. The team reviewed 12 clinical trials of magnesium supplementation in adults and concluded that evidence for improved sleep was inconsistent, with the certainty of evidence rated "low to very low."

Placebo takers also slept better

The research team screened papers and clinical trial registries published through June 1, selecting 12 randomized controlled trials that tested magnesium alone as a sleep intervention.

Because the trials varied widely in participants, formulation, dosage, duration and measurement methods, the team compared results trial by trial rather than combining them into a single figure.

Of five trials that measured insomnia severity using a standardized score, three found improvement in the magnesium group, while two found no difference compared with placebo.

Even where magnesium showed an effect, the difference was modest. In a 2025 trial, participants who took magnesium for four weeks saw their insomnia score — measured on a 28-point scale — drop by 3.9 points, but those who took a placebo also improved by 2.3 points. The net benefit attributable to magnesium was roughly 1.6 points.

Results were even less clear in trials involving patients with other conditions. Those with polycystic ovary syndrome, fibromyalgia or cognitive impairment showed no meaningful difference in overall sleep quality between the magnesium and placebo groups.

Only one trial — conducted in 2002 with 12 participants — used brain-wave monitoring during sleep and confirmed an increase in deep sleep.

When research-grade wrist-worn actigraphy devices were used to measure sleep through movement, no clear difference was found between those who took magnesium and those who took a placebo.

Trials using consumer devices such as smart rings produced mixed results, with some showing a benefit and others finding none.

The amount of magnesium used across trials ranged from 75 to 729 milligrams per day, but taking higher doses or supplementing for longer did not produce greater effects.

According to the Office of Dietary Supplements at the National Institutes of Health, supplemental magnesium exceeding 350 milligrams per day in adults can cause diarrhea, nausea and abdominal cramps.

The research team acknowledged a key limitation: most trials did not measure participants' baseline magnesium intake or blood levels before the study began, meaning some trials that found no effect may have enrolled participants who already had adequate magnesium levels.

Even so, the team concluded that the current evidence is insufficient to recommend magnesium as a treatment for insomnia.

dbsdn1110@heraldcorp.com