Sleep / Explainer
Magnesium For Sleep: Why The Form On The Label Matters
18 June 2026
Magnesium is the most recommended sleep mineral in the UK. It's also the most mis-bought, because the word "magnesium" on a label covers several very different things.
The forms, in plain English
Oxide is the cheapest and the most common in supermarket tablets. It's poorly absorbed. A large amount on the label becomes a small amount in you, and it's the form most likely to upset your stomach.
Citrate absorbs better and is fine as a general supplement. It's also mildly laxative, which is not the evening effect most people are after.
Bisglycinate is magnesium bound to glycine, an amino acid with its own sleep research. It's well absorbed and gentle on digestion, which is why it's the form most sleep formulas built on evidence tend to use.
Threonate is newer and studied for getting into the brain, but it delivers less actual magnesium per gram and costs considerably more.
What to check on the label
- The form is named. "Magnesium 375mg" with no form is usually oxide.
- The label shows elemental magnesium, the amount of the mineral itself, not just the weight of the compound.
- The dose is meaningful. Many gummies contain a token amount dressed in good branding.
UK guidance puts the general adult reference intake around 300mg a day for men and 270mg for women, from food and supplements combined. More is not better; very high supplemental doses mostly end in the bathroom.
As with everything in this category: the mineral is the headline, but the form and the dose are the product.
This article is general information, not medical advice. If symptoms are severe, persistent, or worrying you, speak to your GP or a pharmacist.