Comparison guide
Melatonin, magnesium, glycine or valerian for sleep?
Only one of these has consistent evidence of helping you fall asleep, and even that effect is modest. The others rest on small trials, self-reported ratings or reasoning about mechanism, so the useful question is which has any measurable effect and what it costs you in side effects.
The options, compared
| Option | Evidence | Best for | The honest note | |
|---|---|---|---|---|
| Melatonin | Moderate evidence | Falling asleep and jet lag | A meta-analysis found it shortens time to fall asleep by about 7 minutes on average, and a Cochrane review found it effective against jet lag. Take 0.5–5 mg 30–60 minutes before bed; lower doses often work as well as higher ones. | View |
| Magnesium Glycinate | Limited evidence | Gentle magnesium, not a sleep aid | Three small trials in older adults with insomnia suggested faster sleep onset, but certainty was very low, and no trial has tested the glycinate form specifically. Its real advantage is causing less diarrhoea than magnesium oxide. | View |
| Glycine | Limited evidence | Low-risk, thin evidence | The sleep claim rests on small Japanese crossover studies of 3 g before bed, with around 10–15 people each, never independently replicated. Very well tolerated. | View |
| Valerian Root | Limited evidence | Not worth taking | Despite being the most-studied herbal sleep aid, it has not clearly beaten placebo on objective sleep measures, and extracts vary widely. It adds to alcohol and other sedatives and can leave you groggy in the morning. | View |
| L-Theanine | Moderate evidence | Winding down, not sedation | Small improvements in self-reported sleep quality at 200–400 mg before bed, with little change in objective measures; it is not a sedative. Very well tolerated. | View |
Our verdict
Melatonin is the only option here with consistent, if modest, evidence, and it is the reasonable first choice for trouble falling asleep or for jet lag, starting at a low dose. Glycine, L-theanine and magnesium glycinate are low-risk but unproven for sleep, and valerian is not worth taking. Melatonin is prescription-only or dose-restricted in much of Europe, so check the rules where you live.