Magnesium in Yu Sleep

Magnesium glycinate is the second ingredient listed in Yu Sleep's 637 mg "Proprietary Blend," and like the other six ingredients sharing that blend, the label gives no amount for it. Under 21 CFR 101.36(c)(2), US rules require blend ingredients to be listed in descending order of weight, so if Yu Sleep's label complies, magnesium glycinate is the second-largest of the seven ingredients in the blend. Magnesium glycinate also appears a second time, under "Other ingredients" on the same label, a duplication whose cause is unknown. This page checks what magnesium can do for sleep, the doses the studies used, and the safety data, alongside what our Yu Sleep customer reviews found for the product as a whole.

What magnesium does for sleep

Magnesium is a mineral the body needs for normal nerve and muscle function, and researchers have asked whether taking more of it than diet provides can improve sleep, with mixed results. Arab and colleagues (2023), a systematic review of 9 studies covering 7,582 people, found that low dietary or blood magnesium was associated with worse sleep in observational data, but the randomised controlled trials that followed do not agree with that association. Yu Sleep's own sales letter goes further, claiming that "over a dozen studies found that people who supplemented with this exact form [magnesium glycinate] not only fell asleep faster, but also spent longer in restorative stages of sleep" (text sales letter, paragraphs 585 to 588). That claim does not hold up: PubMed lists one human randomised controlled trial of magnesium bisglycinate for sleep, and reviews rate the wider magnesium-and-sleep evidence low to very low quality. The next section names each study behind that rating and what each one actually found.

The evidence for magnesium

Magnesium's evidence for sleep rates weak, built mostly on one small placebo-controlled trial of the exact form Yu Sleep uses and a handful of larger, lower-quality reviews that disagree with each other. The table below lists the four studies behind that rating.

Schuster and colleagues (2025) ran the only randomised trial of magnesium bisglycinate, the same chemical form Yu Sleep lists, in 155 adults aged 18 to 65 with poor sleep. Their 250 mg elemental magnesium dose, taken daily for 4 weeks, lowered Insomnia Severity Index scores by 3.9 points against 2.3 points for placebo (p=0.049), a small effect (Cohen's d=0.2). Mah and Pitre's 2021 meta-analysis pooled 3 randomised trials in 151 older adults using 320 to 729 mg of elemental magnesium a day as oxide or citrate, not glycinate, over 20 days to 8 weeks: sleep onset latency fell by 17.36 minutes and total sleep time rose by 16 minutes, though that second result did not reach statistical significance, and the authors rated the underlying trials low to very low quality. Lopresti and colleagues' 2026 systematic review of 12 randomised trials concludes that current evidence does not support oral magnesium as a routine treatment for insomnia. None of these four studies tested Yu Sleep's product; the one trial that matches its chemical form used a dose the next section compares against what Yu Sleep's label allows.

The dose in Yu Sleep vs the study doses

Yu Sleep's magnesium amount is not disclosed, so it cannot be checked against the study doses directly; the most that can be worked out is a conditional ceiling, based on the label's ingredient order rather than a measurement. If the blend is listed by weight, as US rules require, magnesium glycinate, second in the 637 mg blend, could hold at most about 318 mg per serving. At the roughly 14% elemental share of magnesium bisglycinate, that works out to about 45 mg of elemental magnesium. That estimate is not a hard ceiling either: magnesium glycinate is also listed a second time under "Other ingredients," a component outside the 637 mg blend with no weight limit attached to it, so the true amount in the bottle could sit above or below the conditional estimate.

Set against the doses the studies used, the gap runs large either way:

• Studied dose that matches Yu Sleep's chemical form (Schuster et al., 2025, bisglycinate): 250 mg elemental magnesium a day, about five and a half times the conditional ceiling.
• Conditional ceiling for Yu Sleep (if the blend is listed by weight): about 45 mg elemental magnesium at most.
• Larger reviewed trials (Mah and Pitre, 2021, as oxide or citrate): 320 to 729 mg elemental magnesium a day.

Against these numbers, the vendor's claim that "over a dozen studies" back this exact form, at whatever amount Yu Sleep contains, is contradicted: the one relevant trial used a stated dose far above what Yu Sleep's undisclosed amount could plausibly reach.

Safety and interactions

Magnesium is generally considered safe at typical supplement doses, and the risks in the safety data are mostly about high intakes or specific medications, not ordinary use. The NIH Office of Dietary Supplements sets a Tolerable Upper Intake Level of 350 mg a day for supplemental magnesium in adults; that figure comes from a saved Wayback copy of the NIH fact sheet, since the live site blocked automated access when this page's research was checked, and it should be re-confirmed on the live page before it is treated as current. High intakes from supplements, above that level, can cause diarrhea, nausea and abdominal cramping, according to the National Center for Complementary and Integrative Health. Magnesium can also interact with several medications:

• Oral bisphosphonates
• Tetracycline and quinolone antibiotics
• Diuretics and proton-pump inhibitors, which can affect the body's magnesium status

People with impaired kidney function are generally advised to use caution with magnesium supplements. Because Yu Sleep's own magnesium amount is undisclosed, a buyer has no way to check it against the 350 mg upper limit; see our Yu Sleep side effects page for the full safety picture across all 10 ingredients.

Magnesium alone vs magnesium inside Yu Sleep

A stand-alone magnesium glycinate supplement lets you choose a dose, such as the 250 mg of elemental magnesium the one relevant trial used, and know that is what you are taking; in Yu Sleep, magnesium sits at an undisclosed amount inside a blend with six other ingredients. Yu Sleep's conditional ceiling, about 45 mg of elemental magnesium at most, is not a hard number either, since magnesium glycinate is also listed under "Other ingredients" outside the 637 mg blend. Magnesium is one of seven ingredients sharing that blend, and the label states no amount for any of them, so a buyer cannot isolate what dose of magnesium, if any, they are taking alongside the tart cherry, apigenin, lemon balm, 5-HTP, L-theanine and GABA that share the same 637 mg. Whether a liquid drop delivers magnesium any differently from a capsule or tablet is a separate, format-level question that the magnesium sleep trials above did not test; see sleep drops work better than pills for that comparison.

Bottom line

On magnesium specifically, not on Yu Sleep as a whole, the evidence is weak: one small trial found magnesium bisglycinate may help some people fall asleep faster in small trials at a stated 250 mg elemental dose, not the "over a dozen studies" the sales copy claims, and Yu Sleep does not disclose enough about its own blend to say whether that trial's dose is even in the bottle. Of the 14 readable buyer reports we analyzed for the product overall, 64% report no noticeable effect and 14% report improved sleep, too small and too mixed a sample to credit or blame magnesium specifically. For the fuller picture on price, refunds and what buyers say about Yu Sleep, read our full review.