Key Topics Covered
Magnesium works by increasing GABA which helps you enter a more relaxed state, theoretically assisting with falling asleep.
Anecdotal Evidence
- We see heaps of examples of people and clients who have tried magnesium for sleep and have reported benefits
- Pros and cons of anecdotal evidence:
- One major con is the lack of placebo control and the fact that other variables can change in the real world.
- But one pro is that we actually don’t have heaps of research on this topic, so anecdotal evidence is slightly more relevant than it otherwise would be.
What Happens if You Have Too Little Magnesium?
- While there is not a lot of research, it is clear that magnesium deficiencies and very low intakes of magnesium in general are linked with worse sleep.
- This could be addressed through either food or supplements.
- The RDI is 400-420mg for men and 310-320mg for women.
- Having a sub-optimal intake of magnesium is common.
- Having a deficiency as defined by a blood test is quite rare.
- Other definitions of deficiency based around intracellular magnesium are reportedly quite common, but we can’t test that easily. It’s not common and is quite expensive.
Magnesium and Insomnia
- One of the most cited studies on this topic involved 46 older adults with insomnia. They compared 500mg magnesium supplementation to a placebo.
- Overall, the magnesium group got significantly better quality and quantity of sleep.
- When interpreting this though it is worth highlighting that older people are more likely to have lower levels of magnesium due to a combination of lower dietary intake of it, and lower levels of absorption.
- We also expect to see larger improvements in sleep quality and quantity in insomnia than we do in other areas of sleep research. So that may also be why it is more clear here.
- A 2021 systematic review of magnesium and insomnia found 3 RCTs. And overall people got to sleep an average of 17 minutes quicker and had a total increase in sleep time of 16 minutes.
Magnesium and General Sleep
- What if you don’t have insomnia but just want to optimise things?
- Higher intakes of dietary magnesium intake have been linked with better sleep.
- RCT’s that have been more tightly controlled have mixed findings though.
- While most people have what is considered an average or sub-optimal intake of magnesium, RCT’s haven’t really found evidence that supplementing beyond these average intakes has found clear benefits.
- It is relatively cheap and safe though, so it is an option that is easy to try. Plus it is likely to be more beneficial if your magnesium intake is lower than average.
Food vs Supplements
- Since there clearly has been a link between better dietary intake and sleep, it makes sense to focus on getting sufficient amounts through food.
- If you’re not getting enough through food, it makes sense to supplement.
- One argument that could also be relevant is that the acute effect of magnesium might be relevant. Supplement dosages are often 300mg, which can be a lot to get through food. Timing that 1 hour before bed could have benefits unique to supplementation.
Other Notes
- Restless Legs Syndrome – a lot of people anecdotally report magnesium helping with restless leg syndrome. A 2019 systematic review on the topic had mixed findings as what not overly promising. Maybe it is worth trialing if interested. But it’s also clearly not as consistently effective as some people make it seem.
- Side effects – high dose magnesium supplements can have side effects of diarrhoea, nausea and vomiting. For context, some supplements like magnesium citrate are commonly used as a laxative.
Type & Dosage
- Most of the research has not looked at the type of supplement specifically. Magnesium Glycinate is the most common option used for this purpose. But keeping in mind that we don’t really have much clear evidence on this topic, we are pretty open minded about various forms of supplementation.
- The standard dosage for supplementation is 300mg, around 1 hour before bed.
Relevant Links / Resources
Blog Posts
Studies Mentioned