New Study on Magnesium Casts Doubt on Sleep Benefits

When it comes to dietary supplements that support sleep quality, magnesium is typically rated one of the best. Magnesium doesn't necessarily help you fall asleep the way melatonin does, but it's supposed to help you stay asleep without the feeling of grogginess the next day.

A new systematic review , however, casts some doubt on the effectiveness of magnesium for sleep. Researchers looked at 12 randomized controlled trials on magnesium for insomnia or poor sleep, and 3 others on sleep problems caused by leg cramps or restless legs. The studies looked at magnesium on its own, not combined with any other supplements.

The results paint a mixed and uncertain picture. One study on magnesium bisglycinate, considered one of the highest quality forms of magnesium, showed a small improvement over placebo for insomnia. Another study showed no clear benefit compared to placebo for overall sleep quality.

A magnesium threonate study that was designed to measure cognitive performance showed daytime impairment improvements as a secondary outcome. However, this was not a consistent finding across all trials.

For objective measures, the results were also mixed. Sleep EEG, which measures brain activity during sleep, changed in one study. But other research-grade tracking devices showed no benefit.

This is not to say magnesium doesn't work or that you shouldn't try it, just that it may not be the slam dunk for improving sleep as we may have thought. It's still a plausible sleep aid based on what magnesium does; it's just unproven at the moment.

Many people have a diet low in magnesium, in which case supplementation would be a good idea. Magnesium is an important mineral involved in hundreds of bodily processes. But if you are using it for sleep, keep your expectations modest. Magnesium is best viewed as a low-risk, low-cost option, not a guaranteed fix.

This story was originally published by Men's Fitness on Nov 7, 2026, where it first appeared in the News section. Add Men's Fitness as a Preferred Source by clicking here.