Is magnesium glycinate better than citrate for sleep?

Magnesium glycinate has a reputation for sleep support, but the evidence for that specific claim is surprisingly thin. No qualifying trial evidence (Cochrane review, major journal RCT, or EMA/EFSA ruling) has established that magnesium glycinate improves sleep compared to other forms. The sleep association largely comes from the glycine component — glycine on its own has some preliminary trial support for sleep quality — but that hasn't been tested head-to-head against citrate in sleep trials.

Magnesium citrate, meanwhile, has EU-authorised claims for contributing to normal muscle function and reduction of tiredness and fatigue 1 — but those are general magnesium claims, not sleep-specific ones.

What the forms actually differ on is absorption and GI tolerance: citrate is better absorbed than oxide, and both citrate and glycinate tend to cause less diarrhoea than oxide at equivalent doses. That's a practical reason people choose glycinate, but it's not a sleep verdict.

The one supplement with actual trial-backed sleep data is L-theanine — a 2025 meta-analysis of randomised trials (897 people, published in Sleep Medicine Reviews) found small improvements in sleep onset and overall sleep quality, though effects were modest.

Bottom line: the glycinate-for-sleep claim is plausible but not yet established by qualifying evidence. The choice between forms is more about gut tolerance than sleep benefit.