Comparison
Melatonin vs. Magnesium
Melatonin or magnesium – what really helps you fall asleep?
The short answer
There is no head-to-head trial; the studies can only be placed side by side. Melatonin has the clearer mechanism: it shifts and stabilises the body clock, and this has been quantified in humans. It works most clearly for jet lag across at least five time zones and in delayed sleep phase syndrome, with sleep onset 38.8 minutes faster; in ordinary insomnia, the largest meta-analysis finds 7.06 minutes. Magnesium's role as a cofactor in more than 300 enzyme reactions is undisputed, but its sleep evidence is thin: one double-blind trial with 155 participants, p = 0.049, effect size d = 0.2, measured by questionnaire only. For melatonin, long-term data are largely missing; for magnesium, diarrhoea is the most common side effect.
The numbers side by side
| Axis | Melatonin | Magnesium | Difference |
|---|---|---|---|
| Human evidenceHow much and how good the data in humans are | 7 | 7 | even |
| MechanismHow well the chain of action is understood | 9 | 8 | Melatonin better studied |
| Safety dataHow well safety has been studied – not how safe it is | 7 | 9 | Magnesium better studied |
| Hype gap10 means: the advertising stays level with the data | 6 | 6 | even |
| Track record of useHow much documented use in humans exists – does not measure whether it works | 9 | 10 | Magnesium in use longer |
| Rating | Supported, with caveats · Supported, with caveats | ||
“Track record of use” measures how long and how widely something has been used in humans – not whether it works. The BK-Score is a subjective assessment by Biohacking Kompakt based on published scoring rules (German). It is not a scientific rating, not the consensus of a professional society and not a medical recommendation.
Why these numbers
Melatonin
The circadian mechanism has been quantified in humans, and there are meta-analyses on sleep onset latency and jet lag. Long-term data are largely missing. According to the BfR, the daily amounts of the products listed in Germany range from 0.1 to 3 mg and are therefore not higher than the 0.5 to 5 mg mostly used in studies; products with up to 10 mg are also offered online.
Magnesium
Very well established biochemically as a cofactor of hundreds of enzymes, with solid studies on blood pressure and sleep quality, but few large outcome trials. Safety is well studied; the marketing of individual salt forms goes beyond the comparative data.
Frequently asked questions
Which helps you fall asleep better, melatonin or magnesium?
The two have not been compared directly. For melatonin, sleep onset latency has been measured: in the largest meta-analysis with 19 studies and 1,683 participants it fell by 7.06 minutes, and by 38.8 minutes in delayed sleep phase syndrome. For magnesium there is one double-blind trial in which the Insomnia Severity Index fell by 3.9 versus 2.3 points on placebo, measured by questionnaire only. A review of 12 trials rates the magnesium evidence as low to very low.
Does melatonin or magnesium help with jet lag?
For melatonin, jet lag is the best-documented use: in the Cochrane review it reduced jet lag in 9 of 10 randomized trials when at least five time zones were crossed. The participants were air passengers, airline staff and military personnel; however, the data date from 2002, and there are no pooled effect sizes. For magnesium, the sources reviewed contain no jet lag data. Its described mechanism runs through enzyme reactions, muscle function and nerve signalling.
Which is safer, melatonin or magnesium?
Magnesium's safety is better studied, with 9 versus 7 out of 10 points in the BK-Score; that means well studied, not harmless. Magnesium's most common side effect is diarrhoea, in up to 37 percent versus 14 percent on placebo in the Cochrane review, and caution is needed in severe kidney failure. For melatonin, the German Federal Institute for Risk Assessment (BfR) lists drowsiness, slower reaction time and morning grogginess among others; long-term data are largely missing.
Are melatonin and magnesium freely available in Germany?
Both are sold as food supplements. Melatonin is also approved as a prolonged-release tablet for the short-term treatment of primary insomnia from age 55, and as a medicine it is prescription-only. In 2024, the BfR could not derive a reliable health-based maximum level and advises against use in children, adolescents, and pregnant and breastfeeding women, among others. For magnesium in food supplements, the BfR has proposed a maximum amount per daily dose, based on a tolerable upper limit from 2001.
See all ratings in the ranking (German app)
Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in a doctor's hands.