Which form of magnesium is most effective for sleep, how much to take, when to take it, who benefits most, and critical drug interactions every adult should know before starting a supplement.
Magnesium is involved in more than 300 enzymatic reactions in the human body, according to the National Institutes of Health (NIH), and plays a documented role in the nervous system pathways that govern sleep. U.S. magnesium supplement sales reached $387 million in the 52 weeks ending October 2025 — a 20% year-over-year increase, according to SPINS market data — making it one of the fastest-growing supplement categories. Yet research from Frontiers in Nutrition indicates roughly half of American adults do not consume the Recommended Dietary Allowance from food alone, and the problem worsens with age. Here are the 10 most important facts from published research before you choose a form or dose.
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Which form of magnesium is best for sleep? Magnesium glycinate (bisglycinate): strongest clinical evidence for sleep · Magnesium L-threonate: best brain absorption, strong cognition + sleep data · Both significantly outperform magnesium oxide (only 4% bioavailability) · Form matters more than brand or dose for sleep outcomesThe research consensus as of 2026 most strongly supports two forms for sleep. Magnesium glycinate (also called bisglycinate) is magnesium bound to glycine, a naturally calming amino acid. It is the form most consistently recommended for sleep by clinicians and the most thoroughly studied in the context of insomnia. A 2025 randomized controlled trial from Leibniz University Hannover, published in Nature and Science of Sleep (PMC12412596), enrolled 155 adults with poor sleep quality and found magnesium bisglycinate significantly improved Insomnia Severity Index (ISI) scores versus placebo. Crucially, glycine itself has independent sleep benefits — it interacts with NMDA receptors and lowers core body temperature, a key physiological trigger for sleep onset. Magnesium L-threonate has unique blood-brain barrier crossing ability, and a 2026 clinical trial published in Frontiers in Nutrition (PMC12832366) found it improved both cognitive performance and sleep quality over 6 weeks.
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How does magnesium actually help with sleep — what is the mechanism? Three distinct biological mechanisms: (1) Activates GABA receptors — the brain’s primary calming neurotransmitter · (2) Supports melatonin production — regulates the sleep-wake cycle · (3) Lowers evening cortisol — reduces stress-driven nighttime arousalMagnesium supports sleep through three documented pathways. First, it activates GABA (gamma-aminobutyric acid) receptors — the same inhibitory neurotransmitter system targeted by prescription sleep medications. Insufficient magnesium means GABA receptors function less efficiently, leaving the nervous system in a state of elevated arousal when it should be winding down for sleep. Second, magnesium is a cofactor in melatonin synthesis. The NIH-cited research shows that magnesium deficiency is associated with disrupted melatonin production, making it harder to fall asleep at a consistent time. Third, magnesium supports the natural evening decline in cortisol — the body’s primary stress hormone. A 2012 double-blind placebo-controlled clinical trial in elderly subjects (PMC3703169) found that magnesium supplementation increased melatonin and renin levels while significantly lowering cortisol, alongside improvements in sleep efficiency. The CARDIA Study (Zhang et al., 2021) found that adults with higher dietary magnesium intake reported longer sleep duration and fewer sleep complaints in a large, diverse cohort.
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What does research actually show about magnesium and sleep quality? Modest but consistent improvements in older adults · 2021 BMC meta-analysis: magnesium shortened time to fall asleep by ~17 minutes; increased total sleep time by ~16 minutes · Best evidence in people who are deficient or in older adults · Not a cure; evidence strongest for sleep initiation and efficiencyThe published clinical evidence is promising but not definitive. A 2021 systematic review and meta-analysis published in BMC Complementary Medicine and Therapies (Mah & Pitre) analyzed three randomized trials in older adults and found magnesium supplementation shortened time to fall asleep by approximately 17 minutes and increased total sleep time by around 16 minutes. The landmark 2012 randomized double-blind trial (Abbasi et al., PMC3703169) in 46 elderly individuals with insomnia found 8 weeks of magnesium supplementation significantly improved ISI insomnia scores, sleep efficiency, sleep time, early morning awakening, and serum melatonin levels. The 2025 trial from Leibniz University Hannover (Schuster et al., PMC12412596) with 155 adults confirmed improved ISI scores with magnesium bisglycinate. A 2025 PubMed-indexed trial (Hausenblas et al., Sleep Medicine X) found magnesium L-threonate improved both sleep quality and daytime functioning. Importantly, clinical guidelines do not yet universally endorse magnesium for sleep due to variability in study quality — benefits appear most consistent in those who are deficient or in older adults with poor baseline magnesium status.
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What is the recommended daily amount of magnesium — and how much can I safely supplement? RDA (from all sources — food + supplements): Men 51+: 420 mg/day · Women 51+: 320 mg/day · Adults 19–50: 310–400 mg/day · Safe upper limit from supplements/medications only: 350 mg/day per NIH · Food magnesium does NOT count toward this limit · Start with 100–200 mg elemental magnesium for sleep supportThe NIH Office of Dietary Supplements provides clear guidelines. The Recommended Dietary Allowance (RDA) — the total magnesium you need from all sources combined — is 420 mg/day for men over 51 and 320 mg/day for women over 51. The Tolerable Upper Intake Level (UL) of 350 mg/day applies only to magnesium from dietary supplements and medications, not from food and beverages. This means a person who eats 300 mg of magnesium from food daily can still safely supplement up to 350 mg more without exceeding safe limits — food and supplement intake are evaluated separately for safety purposes. For sleep support specifically, most clinicians recommend starting with 100–200 mg of elemental magnesium (not the total pill weight — check the “elemental magnesium” figure on the label) taken 30–120 minutes before bed. The Council for Responsible Nutrition independently raised its safe upper limit to 500 mg in April 2025 based on new clinical data, though the NIH’s 350 mg remains the standard medical reference. Always check with your doctor before exceeding 350 mg supplemental magnesium.
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Why do older adults need to be especially careful — and especially likely to benefit? Aging reduces intestinal magnesium absorption · Kidney excretion of magnesium increases with age · Nearly 50% of older adults have insomnia (PMC) · Common medications (diuretics, PPIs) deplete magnesium further · A PMC review found sleep disorders and fatigue in older adults frequently misattributed to aging instead of magnesium deficiencyThe relationship between aging and magnesium is particularly important. Multiple age-related changes reduce magnesium status: intestinal absorption of magnesium declines, urinary and fecal magnesium excretion increases, appetite often decreases, and dietary variety narrows — all independently documented in PMC aging research. On top of these physiological changes, many medications commonly used after age 50 directly deplete magnesium. Diuretics (water pills used for blood pressure and heart conditions) increase urinary magnesium loss. Proton pump inhibitors (PPIs like omeprazole, esomeprazole, pantoprazole) — among the most widely prescribed medications in the U.S. — are associated with lower magnesium levels with long-term use, prompting an FDA advisory. A comprehensive PMC review noted that sleep disorders, cognitive problems, and daytime fatigue in older adults may frequently reflect underlying magnesium deficiency that clinicians and patients attribute simply to normal aging. Nearly 50% of older adults experience insomnia according to the Journal of Research in Medical Sciences — and several clinical trials specifically in older adults show meaningful improvement with supplementation.
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What is the best time to take magnesium for sleep? Take 30–120 minutes before bedtime · Glycinate: 30–60 minutes before bed is most commonly recommended · Allow 2–4 weeks of consistent use before judging effectiveness · Magnesium is not a fast-acting sedative — effects build gradually over weeks · Separate from certain antibiotics and bisphosphonates by at least 2 hoursTiming matters for both effectiveness and drug interaction avoidance. For sleep support, the Sleep Foundation and clinical sleep specialists consistently recommend taking magnesium 30–120 minutes before your target bedtime — not at the dinner table hours earlier. This timing aligns magnesium’s peak absorption with the window when GABA activation and cortisol reduction are most relevant for sleep onset. Unlike melatonin or sleeping pills, magnesium does not act as a direct sedative — it does not cause drowsiness on a first dose. The effect is cumulative: sleep improvements typically become noticeable after 2–4 weeks of consistent daily use, particularly in people whose poor sleep reflects underlying magnesium insufficiency or nervous system overactivity. A critical drug interaction timing note from the NIH: magnesium can bind to and reduce absorption of certain antibiotics (tetracyclines, quinolones like ciprofloxacin) and bisphosphonates (like alendronate/Fosamax for osteoporosis). Always separate magnesium from these medications by at least 2 hours. Consult your pharmacist.
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What are the side effects of too much magnesium? Most common: diarrhea, loose stools, stomach cramping (especially with citrate and oxide forms) · High doses: nausea, vomiting · Very high doses (from supplements + medications): low blood pressure, irregular heartbeat · Kidney disease: magnesium supplements can be dangerous — always consult a physician · Magnesium from food: excess rarely causes side effects in healthy peopleThe most common side effect of supplemental magnesium is gastrointestinal discomfort — loose stools, diarrhea, and stomach cramping. This effect is most pronounced with magnesium citrate (which has a well-known laxative effect and is used medically for bowel preparation) and magnesium oxide (poorly absorbed, tends to remain in the intestines longer). Magnesium glycinate is the form least likely to cause digestive upset because it is well-absorbed before reaching the lower intestine. High supplemental doses can cause nausea and vomiting. Extremely high doses from supplements combined with medications can cause clinically significant hypermagnesemia (elevated blood magnesium), with symptoms including low blood pressure, slowed breathing, irregular heartbeat, and in severe cases, cardiac arrest — though this is rare from oral supplementation in people with normal kidney function. The NIH specifically warns that people with impaired kidney function cannot excrete excess magnesium efficiently, making supplementation potentially dangerous for this group. Always consult your doctor before supplementing if you have kidney disease, heart disease, or take prescription medications.
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What foods are richest in magnesium — and can food alone solve the problem? Richest food sources: pumpkin seeds (168 mg/oz) · dark leafy greens (spinach: 157 mg/cup cooked) · legumes and beans · nuts (almonds, cashews) · whole grains · dark chocolate · Cooking in water leaches magnesium — steaming or roasting preserves more · For many older adults, a small supplement alongside food works bestFood is always the preferred source of magnesium, per the U.S. Dietary Guidelines for Americans. The richest natural sources include pumpkin seeds and other seeds, dark leafy greens (spinach, Swiss chard), legumes (black beans, edamame), nuts (almonds, cashews, Brazil nuts), whole grains (quinoa, brown rice, oats), fish (salmon, halibut), dark chocolate (70%+ cocoa), avocado, and bananas. An important preparation note from NIH and PMC aging research: cooking vegetables in water significantly leaches magnesium content — the mineral dissolves into the cooking water. Steaming, roasting, or eating vegetables raw preserves significantly more magnesium. For many older adults, bridging the gap between dietary intake and the RDA through a small supplement (100–200 mg elemental magnesium in the evening) alongside a diet already reasonably rich in magnesium sources is the most practical and safest approach. Attempting to solve a deficiency through diet alone may be difficult for seniors with limited appetite or dietary variety.
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What drug interactions does magnesium have — and which medications deplete it? Interactions requiring separation (≥2 hours): bisphosphonates (Fosamax/alendronate for osteoporosis) · tetracycline antibiotics · quinolone antibiotics (ciprofloxacin) · Medications that deplete magnesium over time: diuretics (water pills) · proton pump inhibitors / PPIs (omeprazole, pantoprazole, esomeprazole) · Consult your pharmacist before starting any magnesium supplementThe NIH identifies several important drug-magnesium interactions that every adult — especially those over 50 — should be aware of. Bisphosphonates (including alendronate/Fosamax, risedronate/Actonel) taken for osteoporosis or bone loss can have their absorption significantly reduced if taken within 2 hours of magnesium. Tetracycline and quinolone antibiotics (like doxycycline and ciprofloxacin) can also bind to magnesium and reduce absorption — space these at least 2 hours apart. Regarding magnesium depletion: diuretics (thiazides and loop diuretics used for high blood pressure, heart failure, and edema) increase urinary magnesium excretion and can cause deficiency over time. Proton pump inhibitors (PPIs — among the most widely prescribed drug classes in the U.S.) are associated with hypomagnesemia with long-term use, leading the FDA to issue a safety communication about this risk. If you take a PPI long-term, discuss periodic magnesium monitoring with your doctor. The combination of a diuretic and a PPI in an older adult — both extremely common — creates a meaningful risk of chronically low magnesium with downstream effects on sleep, muscle function, and cardiovascular health.
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How do I choose a quality magnesium supplement — what should the label say? Look for: “elemental magnesium” amount on label (not just total pill weight) · USP Verified seal or NSF Certified for Sport seal (third-party purity testing) · Form: glycinate or bisglycinate for sleep (these are the same compound) · Avoid: oxide form for sleep (4% bioavailability); oxide is marked for laxative use · Typical serving: 100–200 mg elemental magnesium for sleepReading a magnesium supplement label correctly is essential because the label can be misleading. A 500 mg magnesium glycinate capsule does not contain 500 mg of elemental magnesium — the “500 mg” refers to the weight of the entire magnesium glycinate compound, which is magnesium bound to glycine molecules. The actual elemental magnesium content is typically 50–80 mg per 500 mg capsule. Always look for a line on the Supplement Facts panel that specifically states “Magnesium (as magnesium glycinate)” with the elemental magnesium content shown separately. The Sleep Foundation and Cleveland Clinic both specifically recommend choosing products that carry a third-party testing seal — USP Verified (U.S. Pharmacopeia) or NSF Certified/NSF International. These seals confirm the supplement contains what the label claims, is not contaminated with heavy metals or harmful substances, and was manufactured under quality-controlled conditions. USP and NSF certification are independently earned and carry genuine quality assurance meaning — they are the most trusted indicators of supplement quality in the United States.
Sources: NIH ODS ods.od.nih.gov (RDA 420/320mg; UL 350mg supplements only; food Mg doesn’t count toward UL; 300+ enzymatic reactions; drug interactions bisphosphonates/tetracyclines/quinolones/diuretics/PPIs; kidney disease contraindication; deficiency signs); PMC3703169 Abbasi 2012 (46 elderly 8 weeks 500mg; improved ISI sleep efficiency early waking melatonin cortisol); PMC12412596 Schuster 2025 Leibniz Hannover (155 adults bisglycinate improved ISI RCT); PMC12832366 Lopresti & Smith Jan 2026 Frontiers in Nutrition (L-threonate 6-week RCT cognition and sleep quality); PMID 40567408 Hausenblas 2025 Sleep Med X (L-threonate sleep quality + daytime function); Mah & Pitre 2021 BMC meta-analysis (17.36 min fall asleep; 16 min sleep time; 3 trials older adults); Zhang CARDIA 2021 (dietary Mg longer sleep duration less complaints); budgetseniors.com Mar 2026 (SPINS $387M 20% YOY; ~50% US below RDA Frontiers 2026; Council for Responsible Nutrition 500mg Apr 2025; glycine lowers core body temp; threonate crosses BBB; 4% oxide bioavailability; malate daytime not bedtime; FDA PPI hypomagnesemia advisory); sleepfoundation.org Nov 2025 (USP/NSF seals; 350mg UL; melatonin vs magnesium); sliiip.com / sleep doctor Apr 2026 (GABA NMDA cortisol mechanisms; oxide 4% poor; not a sedative; RLS supportive); seniorcitizenwellbeing.com Mar 2026 (100-200mg starting; PPIs diuretics deplete; serum Mg = blood not body stores; 1-2hrs before bed); bodyspec.com Apr 2026 (30-120min before bed; separate antibiotics bisphosphonates; food first)
Sources: NIH ODS; Mah & Pitre 2021 BMC; Frontiers in Nutrition 2026; budgetseniors.com Mar 2026; sliiip.com Apr 2026
A label saying “500 mg Magnesium Glycinate” does not mean 500 mg of usable magnesium. That 500 mg includes the weight of the glycine molecules attached. Always look for the “elemental magnesium” figure on the Supplement Facts panel — this is the amount your body can actually absorb and use. A 500 mg magnesium glycinate capsule typically provides 50–100 mg of elemental magnesium. Dose your magnesium based on elemental magnesium content, not total compound weight.
Sources: PMC12412596 Schuster 2025 (bisglycinate 155 adults improved ISI); PMC12832366 Lopresti Jan 2026 Frontiers Nutrition (L-threonate 6-week RCT sleep + cognition); PMID 40567408 Hausenblas 2025 Sleep Med X (L-threonate sleep + daytime function); PMC3703169 Abbasi 2012 (oxide 500mg 8 weeks elderly improved sleep + melatonin + cortisol); budgetseniors.com Mar 2026 (oxide 4% bioavailability; malate daytime not bedtime; glycine body temp reduction; threonate MIT BBB crossing); sliiip.com Apr 2026 (oxide 4% confirmed; glycinate GI tolerability; not a sedative); clinicaltrials.gov NCT07015047 (L-threonate deep sleep HRV ongoing completion Jul 2026)
Based on the research literature, magnesium supplementation is most likely to improve sleep for people in these groups:
- Older adults (over 50): The strongest and most consistent evidence for sleep benefit comes from clinical trials in older adults, who are disproportionately magnesium-deficient due to reduced absorption, increased excretion, and medication use. If you are over 50, regularly take a diuretic or PPI, and struggle with sleep, addressing potential magnesium deficiency is a medically reasonable first step — discuss with your doctor.
- People with anxiety-driven or hyperarousal insomnia: If your sleep difficulty is characterized by a racing mind, physical tension, difficulty “switching off,” or a general state of alertness when you should be winding down — these are hallmarks of nervous system overactivity. Magnesium’s role in GABA function makes it most relevant for exactly this type of sleep problem.
- People who eat a diet low in magnesium-rich foods: If your diet is low in leafy greens, nuts, seeds, legumes, and whole grains — common in highly processed diets — supplementation is more likely to produce noticeable effects by addressing a genuine deficit.
- People with Restless Legs Syndrome (RLS): Some research supports magnesium as a supportive wellness strategy for the uncomfortable leg sensations that prevent sleep onset. The evidence is not definitive, but magnesium is widely discussed in clinical practice as part of a broader approach.
- Magnesium is less likely to help: People who already eat a nutrient-rich diet high in magnesium-rich foods and whose sleep problems stem from sleep apnea, pain, frequent urination, or circadian disruption (like shift work) — these require targeted evaluation and treatment beyond supplementation.
Magnesium and melatonin are fundamentally different and work through different mechanisms:
- Melatonin is a hormone that directly signals to your body that it is nighttime. It is fast-acting (effects within 30–60 minutes) and works best for circadian rhythm issues — jet lag, shift work, delayed sleep phase, or difficulty falling asleep at your target bedtime. The NIH recommends starting with the lowest effective dose (0.5–1 mg) because most over-the-counter products are significantly overdosed at 5–10 mg. Melatonin is not a sedative and should not be used habitually long-term without medical guidance.
- Magnesium is a mineral that supports the underlying biochemical environment for sleep quality — GABA activation, melatonin synthesis support, cortisol regulation, and muscle relaxation. Its effects build gradually over 2–4 weeks of consistent use. It works best for sleep maintenance difficulty, nervous system overactivity, stress-driven waking, and the kind of poor sleep quality associated with magnesium deficiency.
- The practical guidance: If you struggle primarily to fall asleep at your intended bedtime, melatonin (0.5–1 mg, 1 hour before bed) may be more directly helpful. If you fall asleep reasonably but wake repeatedly, sleep lightly, feel unrefreshed, or experience tension and anxiety at night, magnesium glycinate is the more appropriate choice. They can be used together and are not contraindicated — but always discuss with your doctor, especially if you take other medications.
- Sleep apnea symptoms: Loud snoring, gasping or choking during sleep, waking with headaches, or excessive daytime sleepiness are warning signs of sleep apnea — a serious medical condition requiring evaluation and treatment (typically CPAP therapy). No supplement addresses sleep apnea. Untreated sleep apnea increases risk of heart disease, stroke, and cognitive decline.
- Insomnia lasting more than 3 months: Chronic insomnia (difficulty sleeping 3+ nights per week for 3+ months) should be evaluated by a physician. Cognitive Behavioral Therapy for Insomnia (CBT-I) is the first-line recommended treatment per the American Academy of Sleep Medicine — it outperforms sleep medications and supplements in clinical trials for long-term outcomes.
- You take prescription medications: Before starting any magnesium supplement, tell your pharmacist all the medications you take. Drug-magnesium interactions are real and clinically significant — especially with diuretics, PPIs, bisphosphonates, and certain antibiotics.
- You have kidney disease: The NIH explicitly warns that people with impaired kidney function cannot safely excrete excess magnesium. Any magnesium supplementation in the setting of kidney disease requires physician supervision and monitoring.
- You have signs of magnesium deficiency: Loss of appetite, persistent fatigue, muscle cramps, numbness or tingling, irregular heartbeat, and personality changes are early-to-moderate symptoms of magnesium deficiency per the NIH. These warrant a serum magnesium test and medical evaluation rather than self-supplementation.
Sources: sliiip.com / sleep doctor Apr 2026 (who benefits most; anxiety/overarousal subtype; RLS; food-based deficiency; what won’t it help); sleepfoundation.org Nov 2025 (melatonin vs magnesium distinction; timing; low dose melatonin 0.5-1mg); NIH ODS (kidney disease warning; deficiency symptoms loss of appetite nausea fatigue weakness muscle cramps numbness irregular heartbeat); American Academy of Sleep Medicine (CBT-I first-line treatment); budgetseniors.com Mar 2026 (older adults absorption deficits; PMC aging review misattribution); healthiqlab.com 2025 (renal impairment caution; NMDA GABA mechanisms)
- Step 1 — Talk to your doctor or pharmacist first. Particularly important if you take any prescription medication, have kidney disease, or have any chronic health condition. Ask specifically about drug interactions with your current medications — especially if you take diuretics, PPIs, bisphosphonates, or antibiotics.
- Step 2 — Choose magnesium glycinate (bisglycinate) as your starting form. It has the strongest clinical evidence for sleep, is the gentlest on the digestive system, and is widely available. Avoid magnesium oxide (4% absorption, primarily a laxative). If you also have concerns about memory or cognitive health, magnesium L-threonate is a well-researched alternative at a higher price point.
- Step 3 — Start low: 100–200 mg elemental magnesium, 30–60 minutes before bed. Read the label for “elemental magnesium” — not the total compound weight. Choose a product with a USP Verified seal or NSF Certified seal for third-party quality assurance. Give it at least 2–4 weeks of consistent use before judging effectiveness.
- Step 4 — Supplement the diet, don’t replace it. Increase magnesium-rich foods alongside any supplement: pumpkin seeds, spinach, almonds, legumes, dark chocolate, whole grains. Eating magnesium-rich foods gives your body magnesium alongside co-factors present in whole foods that enhance absorption — something a supplement alone cannot replicate.
This guide is independently researched for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Supplement information is based on published peer-reviewed research and official NIH guidelines as of April 2026. Always consult your physician or pharmacist before starting any new supplement, particularly if you take prescription medications, have kidney disease, or have any chronic health condition. Research findings on magnesium and sleep are promising but not definitive — individual responses vary. The NIH 350 mg/day supplemental upper limit remains the standard medical reference. Brand names are not endorsed.
Primary sources: NIH ODS ods.od.nih.gov Magnesium Health Professional Fact Sheet (RDA 420/320mg adults 51+; UL 350mg supplements only; 300+ enzymatic reactions; drug interactions bisphosphonates tetracyclines quinolones; diuretics PPIs deplete; kidney disease warning; deficiency signs); PMC3703169 Abbasi et al 2012 Journal of Research in Medical Sciences (46 elderly 8 weeks 500mg oxide double-blind RCT; improved ISI sleep efficiency early waking melatonin cortisol; 50% older adults insomnia); PMC12412596 Schuster et al August 2025 Nature and Science of Sleep (155 adults poor sleep magnesium bisglycinate improved ISI randomized placebo-controlled; Leibniz University Hannover; 18-65 years); PMC12832366 Lopresti & Smith January 2026 Frontiers in Nutrition (magnesium L-threonate Magtein 6-week RCT; cognitive performance sleep quality adults; Murdoch University); PMID 40567408 Hausenblas et al June 2025 Sleep Medicine X (magnesium L-threonate improved sleep quality daytime functioning RCT); Mah & Pitre 2021 BMC Complement Med Ther (systematic review meta-analysis 3 RCTs older adults; ~17.36 min fall asleep; ~16 min total sleep; limited evidence quality); Zhang et al 2021 Sleep CARDIA study (dietary Mg longer sleep duration fewer complaints diverse cohort); budgetseniors.com Mar 2026 (SPINS 2026 $387M 20% YOY; Frontiers 2026 ~50% US below RDA; PMC aging review; glycine lowers core body temp; Council for Responsible Nutrition 500mg Apr 2025; oxide 4% bioavailability; malate daytime; FDA PPI hypomagnesemia advisory); sleepfoundation.org Nov 2025 (USP/NSF seals; 350mg UL; melatonin vs magnesium; low dose melatonin 0.5-1mg); sliiip.com / sleep doctor Apr 2026 (GABA NMDA cortisol mechanisms; who benefits most; oxide 4% poor; not sedative; RLS); seniorcitizenwellbeing.com Mar 2026 (100-200mg starting; PPIs diuretics aging; serum Mg test limitation; 1-2hrs before bed); bodyspec.com Apr 2026 (start 100-200mg elemental; separate antibiotics bisphosphonates ≥2hrs; food first; USP NSF); healthiqlab.com 2025 (NMDA antagonist; GABA cofactor; 225-500mg adjunctive reasonable; renal impairment caution; Harvard Health 2025); clinicaltrials.gov NCT07015047 (L-threonate deep sleep HRV athletes ongoing 2026)