Compound or practice · Supplement
Magnesium L-Threonate
The magnesium form built to cross the blood–brain barrier — promising for sleep quality, thin on hard outcomes.
- Overall grade
- Grade B
- Last revised
- 4
- graded outcomes
- 3
- references listed
A hand-written entry in Prometheus's bundled library. Its grades are the entry's own reading of the evidence, not a peer-reviewed review.
4 at grade B · 4 at grade C — 8 graded rows
What is known
Each outcome with its grade (how strong the evidence is, A to D), the size of the effect where the entry records one, and how often studies agree.
- Subjective sleep qualityEvidence grade B
3-week RCTs positive; small samples
Moderatemixed
- Deep sleep (wearable-measured)Evidence grade B
Effect concentrates in poor sleepers
Smallmixed
- Working memory (older adults)Evidence grade B
One strong RCT, needs replication
Smalllow
- AnxietyEvidence grade C
Downstream of sleep improvement, not direct
Unclearlow
Conditions
How the entry reads its effect on diagnosed conditions: the direction first, then the grade. Never a substitute for the person who treats you.
- Insomnia ImprovesEvidence grade BSleep-efficiency gains concentrate in poor sleepersGrade B
- Age-related cognitive decline May improveEvidence grade COne strong RCT in older adults; needs replicationGrade C
- Anxiety May improveEvidence grade CSmall trials; likely downstream of better sleepGrade C
- Migraine May improveEvidence grade CGeneral magnesium-repletion evidence — any form works hereGrade C
What is uncertain
Read off the same rows as above. Nothing here is added that the entry does not itself record.
- Thin evidence: Anxiety (grade C).
- Studies disagree: Subjective sleep quality (mixed agreement); Deep sleep (wearable-measured) (mixed agreement); Working memory (older adults) (low agreement).
Up: sleep efficiency %. Across: weeks. The 3-week RCT trajectory in poor sleepers — wearable deep-sleep minutes follow the same shape.
The evidence in words
What it is
Magnesium bound to L-threonic acid, engineered to raise brain magnesium — something citrate and glycinate barely do. The animal data on synaptic density is striking; the human literature is younger and smaller.
What the evidence shows
Human RCTs show improvements in subjective sleep quality and next-day alertness over 3 weeks, and one well-run trial found working-memory gains in older adults. General magnesium repletion (any form) reliably helps sleep only when you were deficient — threonate's edge is specifically the brain delivery, at a much higher price per elemental mg.
What to expect
Evening dose → most users report deeper-feeling sleep within 1–2 weeks, showing up as higher sleep-efficiency and deep-sleep minutes on wearables. If your magnesium intake is already good and sleep is fine, expect little.
How it is used
As the entry records it, from the studies it summarises. Not a recommendation for you — doses that suit a trial population may not suit you.
- Standard
- 1.5–2g (≈144mg elemental Mg) 60–90 min before bed. GI tolerance is excellent vs citrate/oxide.
- Stacking
- Pairs cleanly with glycine 3g; skip stacking with sedatives.
Goes with
- AshwagandhaThe evening stack for stress-driven insomniaEvidence grade B
- Sleep architectureThe behavioral base this builds on — fix the schedule firstEvidence grade A
Questions people ask
Why not cheap glycinate?
If your goal is repletion or general relaxation, glycinate is fine and 5× cheaper. Threonate's case is brain magnesium specifically — sleep architecture and cognition.
Morning grogginess?
Uncommon; if it happens, shift the dose earlier in the evening.
Related reading
Entries that share this one's tags or conditions.
- ApigeninThe chamomile flavone behind the bedtime-tea calm — mild, benign, thinly studied as an isolated supplement.Evidence grade C
- L-Tryptophan / 5-HTPSerotonin/melatonin precursors with modest sleep-and-mood signals — and the sharpest serotonergic-drug caution on the shelf.Evidence grade C
- MelatoninA circadian signal, not a sedative — brilliant for jet lag and shift work at low doses, mediocre as a nightly sleeping pill.Evidence grade B
- Tart CherryA natural melatonin-and-anthocyanin source with small sleep and exercise-recovery signals.Evidence grade C
Sources
As this entry records them: title, journal and year. None carries a DOI or PubMed id, so none is linked as a verified paper. Each link searches PubMed for the title; check that what you find is what the entry describes.
- 1.Magnesium L-threonate and sleep quality: randomized trial — Sleep Med, 2024. Search PubMed (opens in a new tab)
- 2.Enhancement of learning and memory by elevating brain magnesium — Neuron, 2010. Search PubMed (opens in a new tab)
- 3.Magnesium status and sleep: meta-analysis — Nutrients, 2022. Search PubMed (opens in a new tab)
Last revised . A grade is this entry's reading of the evidence, not medical advice.