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Can Magnesium Make You Tired? What About the Next Day?

Magnesium may make you tired and help you sleep, but it probably can’t make you sleepy during the day or make you feel tired the day after taking it.
Written by
Jeff Kahn, M.S., Rise Science Co-Founder
Reviewed by
Chester Wu, MD, Rise Science Medical Reviewer
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We regularly update our articles to explain the latest research and shifts in scientific consensus in a simple and actionable way.
Woman taking magnesium supplement

Can Magnesium Make You Tired? 

  • Magnesium can make you tired in the sense that it may help you drift off and get more sleep. It can relax your muscles, reduce anxiety, and help you fall asleep faster. More research is needed, though, as it may not improve sleep for everyone.  
  • Magnesium probably can’t make you tired the next day or during the day unless side effects from the supplement — like diarrhea and nausea — have disturbed your sleep last night. 
  • Taking too much magnesium in supplement form can cause lethargy, however, so it’s important to stick within safe limits. 
  • The RISE app can help you improve your sleep and energy levels by helping you get enough sleep for you and stay in sync with your body clock. It can also help you build healthy sleep habits that help you get a good night’s sleep — with or without magnesium. 

Magnesium is an essential mineral found in food sources like nuts, seeds, and leafy vegetables. Magnesium helps with everything from bone health and blood sugar regulation to transporting calcium and potassium into your cells, which supports muscle function and normal heart rhythms. It’s also sold as a supplement — often to help you sleep. 

But can taking a magnesium supplement make you sleepy? And if you’re feeling tired during the day, is popping a magnesium pill to blame? 

More research is needed, but magnesium may improve your sleep and energy levels — if you take it correctly.

Below, we’ll dive more into whether magnesium can make you tired.

Did you know? Sleepiness and tiredness aren’t the same thing. Sleepiness is when you could fall asleep if you tried. Tiredness is when you feel fatigue, but you can’t necessarily sleep and sleeping might not boost your energy levels. Magnesium may make you feel sleepy (ready for sleep) and tired (drained and fatigued) in some cases.

Advice From a Sleep Doctor

Advice From a Sleep Doctor

“Magnesium won't make you tired exactly, and won't make you tired the next day either.

That's because a magnesium supplemement doesn't function like a traditional sleep aid that makes you drowsy; instead, it helps regulate neurotransmitters and your sleep-wake cycle, to promote relaxation and help you feel sleepy without sedating you. That's why taking magnesium at night is unlikely to leave you feeling groggy or tired the next day, as it supports natural processes of sleep.

But taking too much magnesium can lead to low energy, so be sure to stick to a maximum of 500 mg elemental magnesium if you’re trying the supplement and check with your healthcare provider that it’s safe for you."

Says Dr. Chester Wu, who is double board certified in psychiatry and sleep medicine.

Can Magnesium Make You Tired? 

Yes, taking magnesium may make you sleepy and ready for bed in many ways. It acts as a muscle relaxant, and indirectly increases gamma-aminobutyric acid (GABA), a neurotransmitter that lowers anxiety. It also contributes to the production of the sleep hormone melatonin, which plays a critical role in regulating your circadian rhythm — the internal body clock that helps to control your sleep patterns. Magnesium also helps reduce the stress hormone cortisol, further promoting relaxation and your readiness for sleep.

In some studies, supplemental magnesium has been found to improve: 

  • Sleep onset latency (how long it takes you to fall asleep) 
  • Sleep duration 
  • Sleep efficiency (the measure of how long you spend asleep in bed) 
  • Early morning awakenings
  • Insomnia  
  • Restless leg syndrome 
  • Anxiety and depression symptoms — both of which can cause sleep loss 

Taking magnesium may also help with constipation, migraines, hot flashes, muscle cramps, and leg cramps for some, which can benefit sleep. And it may lower blood pressure and cut the risk of type 2 diabetes, heart disease, and osteoporosis.

And magnesium may make you feel tired via the placebo effect. If you’ve taken magnesium as a sleep supplement you could think yourself into feeling sleepy.

By getting more restful sleep, magnesium may help you feel more energized and awake during the day.

But more research is needed. There hasn’t been enough large-scale, high-quality research specifically focused on magnesium’s effects on sleep. Many clinical trials on magnesium are short, low quality, have contradictory findings, and are done on small sample sizes or on certain populations (like older adults or those with mental health issues, sleep disorders, or medical conditions). Dosages also vary from study to study and some use oral magnesium and other intravenous magnesium, making it hard to draw solid conclusions. 

Plus, it’s unclear if supplements are just beneficial for those with low levels of magnesium — although nearly 50% of Americans don’t get enough of the mineral. 

Beyond this, we all react differently to magnesium supplements and whether it makes you sleepy may depend on the type of magnesium supplement you take. 

Different forms of magnesium have different levels of bioavailability, which affects how much is actually absorbed and used by the body. 

For example, you can buy magnesium citrate, magnesium glycinate, magnesium oxide, magnesium chloride, and magnesium sulfate supplements, which may affect you — and your sleep and energy levels — in different ways.  

Considering magnesium as a sleep supplement? We compare magnesium vs. melatonin here. 

If you feel worse when you take magnesium, something else could be to blame — like sleep debt (sleep you’ve missed out on recently) or circadian misalignment (when you’re out of sync with your circadian rhythm, or body clock). These are common culprits of low energy. 

Expert tip: Many of us don’t know how much sleep we need and therefore may not get enough of it. We looked at how much sleep 1.95 million RISE users aged 24 and up need and found 48% needed eight hours of sleep or more.

The RISE app can tell you how much sleep you need.
How much sleep RISE users need.

RISE can work out how much sleep you need, so you know what to aim for. RISE also tells you if you have any sleep debt and predicts your daily circadian rhythm, so you can get in sync with it. This should help you feel less tired, whether you're taking magnesium or not.

If you’re turning to magnesium because you can’t sleep, there’s more research behind sleep hygiene. These are the habits that are proven to help you fall asleep faster and wake up less often. 

RISE can tell you the best time to do 20+ daily sleep hygiene habits at the right time for your circadian rhythm, which will make them more effective. 

RISE app screenshot showing how much sleep debt you have
RISE works out your sleep debt.

RISE users on iOS 1.202 and above can view their sleep need here, view their sleep debt here, and set up their 20+ in-app habit notifications here

Does Magnesium Make You Sleepy During the Day?

No, taking magnesium probably can’t make you sleepy during the day. It doesn’t act as a sedative, so taking a supplement in the morning or daytime probably wouldn’t cause daytime sleepiness or make you sleepy right away. 

In fact, the opposite may be true. Magnesium may improve your sleep and, therefore, daytime energy levels. 

A 2018 study published in Nutrients found that higher magnesium intake was associated with decreased odds of falling asleep during the day. 

However, this link was found in women, but not in men, and researchers looked at dietary sources of magnesium, not supplements. Plus, there was no link between magnesium intake and daytime sleepiness — just falling asleep. 

Beyond this, magnesium may improve your energy in other ways. 

Magnesium is involved in energy production and energy metabolism — the breakdown of food for energy in your cells. Animal studies have found magnesium supplementation can improve the efficiency of energy metabolism and human studies suggest supplements can improve exercise performance, exercise-related fatigue, and the perception of fatigue. 

Plus, side effects of magnesium deficiency include fatigue and lethargy, and low magnesium is linked with excessive daytime sleepiness, so supplements may improve your energy levels if you’re not getting enough magnesium. But more research is needed to back this up. 

There are a few cases when magnesium could make you tired during the day: 

  • Lethargy is a side effect of magnesium toxicity, which is associated with very large doses of magnesium — typically more than 5,000 mg per day.
  • Even if you don’t take enough to cause magnesium toxicity, taking too much magnesium can cause side effects like nausea, stomach cramps, and diarrhea. These can cause sleep loss, which can make you feel sleepy during the day.
  • Magnesium can interact with medications like antibiotics and proton pump inhibitors, which may cause hypomagnesemia (magnesium deficiency), which could cause low energy levels. 

As with all things magnesium, it may depend on how much you take, which form of magnesium you take, your natural levels of the mineral, and how you individually react to supplements. 

Considering a morning supplement? We’ve covered when to take magnesium for sleep here. 

Heads-up: Magnesium probably won’t cause insomnia or restless leg syndrome in most people. It may actually improve these sleep disorders, but more research is needed. 

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Can Magnesium Make You Tired the Next Day?

Magnesium probably can’t make you tired the next day. Tiredness isn’t a common side effect of magnesium supplements (when you take the right amount) and there isn’t any research suggesting magnesium can cause tiredness the next morning if you take it the night before, like some sleep aids.  

In fact, magnesium may help you get more sleep, giving you more energy the next day and morning. 

However, as we mentioned above, if supplements interact with your medication, disrupt your sleep, or you take high levels of magnesium, you may feel sleepy and exhausted the next day. 

It may also depend on the type and amount of magnesium you take and your natural levels of magnesium.  

Can Too Much Magnesium Make You Tired?

Yes, too much magnesium can make you tired. According to the Office of Dietary Supplements at the National Institutes of Health (NIH), very large doses of magnesium —typically more than 5,000 mg per day — have been associated with magnesium toxicity. This is when you have more than 1.74 to 2.61 millimoles of magnesium per liter in your blood. 

Magnesium toxicity can cause side effects like:

  • Lethargy — aka lack of energy
  • Muscle weakness
  • Depression 
  • Vomiting
  • Hypertension (high blood pressure)
  • Urine retention
  • Irregular heartbeat 
  • Cardiac arrest 

Even without magnesium toxicity, the side effects of taking excess magnesium include diarrhea, nausea, and abdominal cramping. These side effects can keep you up at night, which can make you feel sleepy the next morning or day. 

As supplemental magnesium can relax your muscles, increase melatonin, and have calming effects, taking too much can make you feel drowsy in this way before bed.

Expert tip: Dr. Wu advises not taking more than 500 mg of elemental magnesium per day. 

Elemental magnesium refers to the actual amount of pure magnesium available for absorption from a supplement, regardless of the compound it's bound to, such as magnesium oxide or magnesium citrate. 

This is in contrast to the National Institutes of Health (NIH) guidelines that recommend a tolerable upper intake level (UL) of 350 mg per day of magnesium from supplements. This NIH guideline pertains specifically to the total amount of magnesium ingested from non-food sources, not just the elemental portion, to prevent adverse side effects associated with excessive intake. 

When you’re choosing a magnesium supplement, it’s important to understand the difference between total magnesium and elemental magnesium to ensure safe and effective supplementation!

There’s also a risk of magnesium overdose. Large doses of laxatives and antacids containing magnesium have caused hypermagnesemia (too much magnesium), which can be fatal. 

Check with a doctor before taking magnesium if you’re pregnant, breastfeeding, or have a health condition. They may not be safe for those with kidney disease or cardiovascular disease.

We cover the best dosage of magnesium for sleep here. 

You may not need to take magnesium every day or supplement with magnesium at all. You can get enough magnesium from your diet by eating foods high in magnesium. 

Magnesium-rich foods include: 

  • Cashews
  • Pumpkin seeds
  • Green leafy vegetables
  • Legumes
  • Whole grains
  • Fortified cereals

Check with a healthcare professional to find out if you have low magnesium and if supplements could be beneficial. 

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Feel Less Tired — With or Without Magnesium 

The health benefits of magnesium may include better sleep, but magnesium probably isn’t to blame if you’re feeling tired during the day or the next day after taking a supplement.

If you’re feeling tired, sleep debt and circadian misalignment are the more likely causes. RISE can help you lower your sleep debt and get in sync with your circadian rhythm to eliminate these common causes of fatigue. 

RISE can also guide you through 20+ sleep hygiene habits, which can help you get better sleep without relying on magnesium.

Users say they don’t need any sleep supplements at all when using RISE: 

“I suffer from genetic insomnia and have tried all kinds of medicines, supplements, and pretty much anything and everything else. RISE is the first thing that’s worked. Its estimations of my ideal bedtime for each night are completely accurate, and I’ve been waking up on my own for the first time in my entire life. I’m suddenly able to wake up and do things in the morning instead of feeling drowsy until one in the afternoon.” Read the review

Even better? 80% of RISE users feel more energy within five days.


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Rise is the only app that unlocks the real-world benefits of better sleep.

Instead of just promising a better night, we use 100 years of sleep science to help you pay down sleep debt and take advantage of your circadian rhythm to be your best.

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