Interaction fact sheet · Synergy
Magnesium and melatonin
Compatible combination, little studied as such.
No problematic interaction has been described. Evidence on the combination comes mainly from a small trial in older people, using a product that also contained zinc.
The only trial on the combination
Rondanelli and colleagues recruited 43 residents of an Italian nursing home, with an average age of 78 and primary insomnia. For 8 weeks, one hour before bedtime, they received either 5 mg of melatonin, 225 mg of magnesium and 11.25 mg of zinc mixed into pear purée, or the purée alone. The supplemented group showed marked improvements in sleep quality score (PSQI), total sleep time measured by a sensor, ease of falling asleep and alertness the following morning.
The result is clear, but it involves three substances at once: it is impossible to know what is attributable to melatonin, magnesium, or zinc. It also concerns a very specific population, in which deficiencies and rhythm disturbances are more common than in active adults.
What each component does on its own
For magnesium, Abbasi and colleagues gave 500 mg per day or a placebo to 46 older adults with insomnia for 8 weeks. Magnesium improved the insomnia severity index, sleep efficiency and time to fall asleep, and increased blood melatonin levels. The meta-analysis by Mah and Pitre includes 3 trials involving 151 older adults: about 17 minutes less time to fall asleep, but no significant effect on total sleep time, with evidence rated as low to very low quality.
For melatonin, Ferracioli-Oda and colleagues conducted a meta-analysis of 19 trials involving 1,683 people: about 7 minutes less time to fall asleep and 8 minutes more sleep. Real but modest effects, more pronounced with higher doses and longer durations.
Cautious approach
If you combine the two, take them in the evening, as in the trial. Start with the lowest melatonin dose that works for you: see our analysis of the melatonin microdosing . For magnesium, the form matters for digestive tolerance: see the comparison of magnesium forms and the magnesium score. If you have renal impairment, do not take magnesium without medical advice.
Limits
Only one trial tests the combination, in 43 older people in residential care, and it adds zinc. Trials on magnesium alone are small and of low quality according to the meta-analysis. No trial compares melatonin alone with melatonin combined with magnesium: we don't know whether the combination works better than either one separately. For persistent insomnia, a consultation remains more useful than a stack.
Main sources
- 01Rondanelli M et al. The effect of melatonin, magnesium, and zinc on primary insomnia in long-term care facility residents in Italy. Journal of the American Geriatrics Society, 2011. PubMed 21226679
- 02Abbasi B et al. The effect of magnesium supplementation on primary insomnia in elderly: a double-blind placebo-controlled clinical trial. Journal of Research in Medical Sciences, 2012. PubMed 23853635
- 03Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults: a systematic review and meta-analysis. BMC Complementary Medicine and Therapies, 2021. PubMed 33865376
- 04Ferracioli-Oda E et al. Meta-analysis: melatonin for the treatment of primary sleep disorders. PLoS One, 2013. PubMed 23691095
Frequently Asked Questions (FAQ)
Should you take magnesium and melatonin at the same time?
In the Rondanelli trial, melatonin, magnesium, and zinc were taken together one hour before bedtime. No data show that another timing would work better or worse, and no sign of incompatibility between the two is reported.
Does magnesium increase melatonin?
In the Abbasi trial, 500 mg of magnesium per day for 8 weeks increased blood melatonin levels in older adults with insomnia. This result has not been replicated in young adults and does not indicate whether the effect adds to that of supplemental melatonin.