A person taking a supplement in bed
Magnesium may help some people get better sleep, but it can take weeks to work.
Panuwat Dangsungnoen / Getty Images
It can take weeks for magnesium supplements to improve your sleep, though results are not guaranteed.
People who have low magnesium levels may see improvements sooner.
Several factors affect magnesium absorption, including the form of magnesium, diet, health conditions, and medications.
Magnesium may improve your sleep quality and help you sleep longer.12 Magnesium does not work instantly, especially if you are using it for the first time.
1. Give Magnesium Time to Take Effect
Some people may notice improvements in sleep within a few weeks of starting magnesium supplementation. However, evidence is mixed, results are not guaranteed, and individual outcomes and timelines vary.12
That said, depending on the form, the body begins to absorb magnesium about one hour after intake, which is why taking it just before bedtime may be best to improve sleep.3
Taking magnesium consistently may help if low magnesium levels are contributing to sleep problems.
2. Faster Improvement May Be Seen In People With Low Magnesium Levels
Studies suggest that people with magnesium deficiency may notice more immediate improvements in their sleep with magnesium supplements compared to those without a deficiency.4
3. Type of Magnesium May Matter
The types of magnesium used in studies to improve sleep include magnesium glycinate, magnesium threonate, magnesium oxide, magnesium lactate, and magnesium L-aspartate.51
The body absorbs inorganic formulations of magnesium, such as magnesium oxide and magnesium sulphate, less than the organic formulations (magnesium glycinate, magnesium threonate, and magnesium taurate).63 Better absorption may help improve magnesium status, which could contribute to sleep benefits in some people.
Magnesium supplementation has been shown to improve sleep quality in some adults:
Magnesium glycinate is commonly used for sleep due to its good tolerability and absorption, though evidence supporting sleep benefits is limited.7
Magnesium threonate has been shown to improve sleep quality in adults with self-reported sleep problems. Animal studies suggest magnesium threonate may increase brain magnesium levels, but the mechanism underlying its sleep effects in humans hasn’t been fully established.1
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4. What You Eat Can Affect Levels
Your diet can affect how much magnesium your body absorbs:8
Soft drinks high in phosphoric acid (such as cola) and foods high in phytates (such as some grains and legumes) may reduce magnesium absorption. Some polyphenols have been shown to interact with magnesium in experimental settings, but their impact on magnesium absorption in humans is less clear.8
Incorporating magnesium-rich foods such as green leafy vegetables (such as spinach), legumes, and whole grains into your diet can enhance the effectiveness of magnesium supplements.
5. Health Conditions Affect Absorption
Certain health conditions can affect how well your body absorbs magnesium and may influence how quickly magnesium works for sleep.
You may observe a slower effect when using magnesium to improve your sleep quality if you:9
Regular alcohol intake (can increase magnesium loss through the urine)
Have gastrointestinal diseases such as Crohn’s disease, celiac disease, or ulcerative colitis
Are diagnosed with type 2 diabetes or insulin resistance
6. Medications Can Reduce Absorption
Medications that can reduce the amount of magnesium your body absorbs include:10
Antacids such as Prilosec (omeprazole)
Some antibiotics (such as tetracyclines or fluoroquinolones)
Oral contraceptives
Diuretics such as Lasix (furosemide)
Before You Start Supplements
Talk with a healthcare provider before starting magnesium supplements, especially if you take medications or have underlying health conditions. They can determine whether magnesium is appropriate for you, review your current medications, and assess for conditions that may increase the risk of side effects.
Magnesium can interact with certain medications, and your healthcare provider can help determine the appropriate dose and form.
Next Steps
If you have difficulty falling asleep for many nights in a row or find yourself constantly waking up due to restlessness, discuss your concerns with your healthcare provider. They will analyze your sleep habits, consider underlying conditions that may be triggering your poor sleep patterns, and recommend appropriate treatment.
