Magnesium L-Threonate review · Sleep and brain
Momentous Magnesium L-Threonate Review (2026): What 145 mg Can and Cannot Do
Sold as a brain targeted form of magnesium, three capsules before bed. We decoded the label, read the one sleep trial on its ingredient, and compared it with Momentous's other night products.
By Sama Alabed · First published 23 Jun 2026 · Facts checked 7 Nov 2026
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3 capsules145 mg magnesium2 g Magtein30 nights
The short answer
A well made, NSF listed magnesium with one small but encouraging sleep trial behind its ingredient. It is not a sedative, it costs about $1.67 a night, and 145 mg is a modest dose.
- Dose145 mg magnesium from 2 g Magtein magnesium L-threonate, 3 capsules. Label
- Timing30 to 60 minutes before bed, every night. Maker
- EvidenceOne 21 day trial in 80 adults found better deep and REM sleep scores than placebo. Small, short and industry linked.
- Testing"Magnesium Threonate" is listed in NSF's Certified for Sport directory (searched 7 Nov 2026).
- Best forAdults who want a nightly, non sedating magnesium. Skip it if you want the cheapest magnesium or a knockout pill.
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The label, decoded
2 grams in the capsules, 145 milligrams of magnesium
What the capsules hold. 2,000 mg of Magtein, the patented magnesium L-threonate compound.
What is magnesium. 145 mg, about 7% of the compound's weight. This is the number to compare with other supplements.
Against the safety limit. NIH sets the adult upper limit for magnesium from supplements and medicines at 350 mg a day. One serving uses 41% of it.
Source data · Momentous label, read 7 Nov 2026; NIH Office of Dietary Supplements, magnesium fact sheet. Bars to scale within each row. Visualized by · samā·says.
When to take it
One rule now: before bed
The product page gives a single instruction: 3 capsules, 30 to 60 minutes before sleep, as part of a steady night routine. That is the direction we follow.
The evidence
One trial, read closely
People
80
Adults aged 35 to 55 who said they slept poorly.
Dose
1 g Magtein a day for 21 days, against a placebo. Momentous's serving is 2 g.
Measured
Sleep scores from an Oura ring plus daytime questionnaires.
Found
Better deep sleep and REM sleep scores, more light sleep time, and better mood, energy and alertness ratings than placebo. No safety concerns reported.
Hausenblas HA et al. Sleep Medicine: X 2024;8:100121. PubMed 39252819 Study
How much weight it carries: early and promising, not settled. It was small and three weeks long, sleep problems were self reported, and one author works for the company that makes Magtein.
Magnesium in general has a longer record. A small 2012 trial in 46 older adults with insomnia found that 500 mg of magnesium a day for 8 weeks improved sleep time and sleep efficiency compared with placebo. Study
Abbasi B et al. J Res Med Sci 2012. PMC3703169
Magnesium also plays a role in cognitive function and synaptic plasticity. Study
NCBI, PMC9786204
Momentous says Magtein crosses the blood brain barrier and raises brain magnesium. Maker Much of that brain level work comes from animal studies.
For example, in rats: Slutsky I et al. Neuron 2010;65(2):165. PubMed 20152124
Which night product
Threonate, Nightly Sleep or Bisglycinate?
Momentous sells three ways to take magnesium at night. Pick the one that matches what you want.
Magnesium on its own, in the brain targeted form
- In it: 145 mg magnesium from 2 g Magtein
- Price: $49.99 one time, about $1.67 a night
- NSF directory: listed
Pick it if you want magnesium alone and value the form with the 2024 sleep trial behind it.
A ready made wind down blend, no melatonin
- In it: 200 mg magnesium as bisglycinate, 200 mg L-theanine, 50 mg apigenin, in 3 capsules
- Price: $59.99 one time, about $2.00 a night
- NSF directory: listed
Pick it if you would rather take one product than build a stack. Do not add Magnesium L-Threonate on top without checking your total: together they reach 345 mg.
The lower cost magnesium, without the brain claims
- In it: 200 mg magnesium as bisglycinate, in 2 capsules
- Price: $16.99 one time, about $0.57 a night
- NSF directory: listed
Pick it if price matters most. It holds more magnesium per serving than the threonate, without the brain targeted form.
Doses, servings and one time prices from each livemomentous.com product page, read 7 Nov 2026. Momentous's Bisglycinate page also suggests Magtein in the morning with Bisglycinate at night; that pairing totals 345 mg of magnesium.
Before you start
Safety, in plain words
- The 350 mg upper limit counts all magnesium from supplements and medicines, including laxatives and antacids. Add them up if you take more than one.
- Higher magnesium doses can cause loose stools or stomach cramps. Momentous says the same.
- Combining Momentous products adds up fast: Magnesium L-Threonate plus Nightly Sleep, or plus Bisglycinate, is 345 mg, just under the limit.
- Magnesium can interact with some medicines, including bisphosphonates for osteoporosis and tetracycline and quinolone antibiotics; diuretics and proton pump inhibitors can change your magnesium levels. Ask a pharmacist how to space them. NIH fact sheet
- Ask your doctor first if you have kidney disease, take prescription medicines, or are pregnant or breastfeeding.
- Sleep that stays poor for weeks deserves a conversation with a clinician, not just a supplement.
Who should skip it
Not the right night tool for everyone
“30 to 60 minutes before bed, paired with a consistent night routine.”Sama, from the earlier review. Still true in November 2026: “I still take magnesium every night before bed.”
- You want to be knocked out. This is not a sedative and does not replace a sleep medicine.
- You want the cheapest magnesium. Momentous's Bisglycinate is about $0.57 a night against $1.67.
- You already take magnesium. Check your total against the 350 mg limit first.
- You have kidney disease. Magnesium needs a doctor's go ahead.
Try it
Magnesium L-Threonate SAMA15
One time with SAMA15: $42.49 for 30 nights, about $1.42 a night. Prices checked 7 Nov 2026.
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Quick answers
Frequently asked questions
Is magnesium L-threonate better than other forms?
It is the form with the most research on brain magnesium, much of it in animals, and one 2024 human sleep trial. For simply topping up magnesium, cheaper forms such as bisglycinate also work. Compare the milligrams of magnesium, not the compound weight.
How much magnesium is in Momentous Magnesium L-Threonate?
145 mg of magnesium in 3 capsules, from 2 g of Magtein. That is 35% of the Daily Value and under the 350 mg upper limit for supplements.
When should I take it, morning or night?
Momentous's directions say 3 capsules 30 to 60 minutes before bed, every night.
How long does it take to work?
Momentous says some people notice sleep changes in about a week and the full effect after about four weeks. The 2024 trial measured changes over 21 days.
Does it replace melatonin?
No. Magnesium is a mineral, not a hormone, and works more quietly. If you use melatonin or a sleep medicine, ask your doctor before changing anything.
Are there side effects?
Loose stools or cramps are the most common, mainly at higher doses. People with kidney disease should not take magnesium supplements without their doctor's advice.
After dark, and beyond
More from our Momentous reviews
For everything that shapes a night, read Sleep Architecture.
For educational purposes only. Nothing here is medical advice; ask a qualified professional before starting any new supplement. As an affiliate, samā·says may earn a commission on qualifying purchases made through links in this post.