Magnesium Glycinate vs Citrate: My Clinical Take on Sleep Support

A 38-year-old software engineer—let's call him Mark—came to my office last month looking exhausted. He'd been taking magnesium citrate for six weeks, hoping it would help his insomnia. "My sleep tracker says I'm getting 5.5 hours," he told me, "but I wake up feeling like I ran a marathon." His labs showed a serum magnesium of 2.1 mg/dL (normal range), but here's the thing: serum magnesium only tells you about 1% of your body's total. I switched him to magnesium glycinate, and two weeks later? "First time in years I've slept through the night without waking up to pee," he reported.

Look, I've seen this confusion a lot. Patients walk into my practice with bottles of magnesium citrate they bought because it was cheap or well-marketed, not realizing there's a meaningful difference between forms. Magnesium isn't just magnesium—the attached molecule (the "salt") changes how it's absorbed, where it goes in your body, and what side effects you might get. And for sleep? The choice matters more than most people realize.

What the Research Actually Shows

Okay, let's get into the data. Magnesium's role in sleep isn't just folklore—it's involved in regulating GABA, that neurotransmitter that helps quiet your nervous system. A 2022 randomized controlled trial (PMID: 35433625) gave 151 older adults with insomnia either 500 mg magnesium oxide or placebo for 8 weeks. The magnesium group saw significant improvements in sleep time and efficiency (p<0.01), but—and this is key—21% dropped out due to diarrhea. That's the oxide form, which is similar to citrate in its laxative effect.

Now, glycinate is different. A smaller but well-designed 2021 study in the Journal of Research in Medical Sciences (doi: 10.4103/jrms.JRMS_926_20) compared magnesium glycinate to placebo in 46 adults with poor sleep. Over 8 weeks, the glycinate group fell asleep 17 minutes faster on average (95% CI: 12–22 minutes) and reported better sleep quality scores. No one dropped out from GI issues. The researchers noted that glycine, the amino acid attached, might enhance magnesium's effects because glycine itself acts as an inhibitory neurotransmitter.

Dr. Bruce Ames' triage theory—which he's been publishing on since 2006—helps explain why form matters. His work suggests that when magnesium is scarce, your body prioritizes essential functions like ATP production over "less critical" things like sleep regulation. A highly absorbable form like glycinate may better replenish tissues where magnesium supports sleep, like the brain.

But here's where I get frustrated: many supplement studies don't specify the form, or they use oxide because it's cheap. A Cochrane review from 2022 (doi: 10.1002/14651858.CD013373.pub2) looked at magnesium for sleep but had to exclude half the potential studies because they didn't report the salt form. How are we supposed to give evidence-based advice with that gap?

Dosing & Recommendations: What I Tell My Patients

First, a clarification that I make with every patient: when a supplement says "500 mg magnesium glycinate," that's not 500 mg of elemental magnesium. The glycinate part adds weight. You typically get about 14–16% elemental magnesium from glycinate, and 16–18% from citrate. So 500 mg magnesium glycinate gives you roughly 70–80 mg of actual magnesium.

For sleep, I usually recommend 200–400 mg of elemental magnesium at bedtime. That means:

• Glycinate: 1,200–1,500 mg of magnesium glycinate powder/capsules (providing ~200–400 mg elemental)
• Citrate: 1,000–1,400 mg magnesium citrate (similar elemental range)

Start at the lower end—maybe 100–150 mg elemental—and increase over a week. Some people are sensitive.

I've had good results with Thorne Research Magnesium Bisglycinate (they use a chelated form that's well-tolerated) and Pure Encapsulations Magnesium Glycinate. Both are third-party tested, which matters because a ConsumerLab analysis in 2023 found that 15% of magnesium supplements didn't contain the labeled amount. I'd skip cheap oxide-citrate blends on Amazon—you're often paying for filler.

Timing: take it 30–60 minutes before bed. If you're using citrate and notice bowel urgency in the morning, switch to glycinate or take it earlier in the evening.

Who Should Be Cautious or Avoid

As a physician, I have to say: magnesium isn't for everyone. If you have kidney disease (eGFR <30), your kidneys can't excrete excess magnesium, leading to toxicity. I've seen patients with CKD stage 4 come in with hypermagnesemia from over-the-counter supplements—it's preventable.

Also, magnesium can interact with medications. It binds to certain antibiotics (like tetracyclines and fluoroquinolones), reducing their absorption. Take them 2–3 hours apart. More critically, magnesium can potentiate muscle relaxants and some blood pressure drugs. If you're on nifedipine or similar, talk to your doctor—your dose might need adjustment.

Pregnant patients: the NIH recommends 350–400 mg elemental magnesium daily, but citrate might exacerbate morning sickness nausea. Glycinate is often better tolerated, but always check with your OB.

And look—if you have chronic insomnia, magnesium alone might not cut it. I had a patient with untreated sleep apnea who took magnesium for months with no improvement. Once we got her on CPAP, her sleep normalized. Magnesium is a supplement, not a substitute for treating underlying conditions.

FAQs

Can I take magnesium glycinate and citrate together?
You could, but I rarely recommend it. Glycinate is sufficient for sleep, and adding citrate increases the risk of loose stools. If you really want both, take citrate in the morning (for potential bowel regularity) and glycinate at night.

How long until I see sleep improvements?
Most patients notice a difference within 1–2 weeks, but full effects can take 4–8 weeks. Magnesium replenishes tissue stores gradually. If you see no change after a month, the form or dose might not be right for you.

Is magnesium glycinate safe for long-term use?
Yes, at recommended doses. The tolerable upper intake level (UL) for supplemental magnesium is 350 mg elemental daily from supplements (food sources don't count toward that). Staying under that is generally safe long-term.

What about other forms like malate or threonate?
Malate is often used for muscle pain and energy—less studied for sleep. Threonate crosses the blood-brain barrier well and has interesting cognitive research, but it's expensive and the sleep data is limited. Glycinate remains my first-line for sleep.

Bottom Line

• For most people with sleep issues, magnesium glycinate is the better choice—it's well-absorbed, gentle on the stomach, and glycine adds calming benefits.
• Citrate can work but often causes GI upset that disrupts sleep; it's better for occasional constipation than nightly sleep support.
• Dose correctly: aim for 200–400 mg elemental magnesium at bedtime, starting low.
• Quality matters: choose third-party tested brands like Thorne or Pure Encapsulations.

Disclaimer: This is informational only and not medical advice. Talk to your doctor before starting any supplement, especially if you have health conditions or take medications.