Why I Started Taking Magnesium L-Threonate — And Why I Think Every Woman Over 40 Should Know About It
By Ellen Potter | Potley's Apothecary
Since I was pregnant with my first son, over 17 years ago now, I have slept very lightly. I'm lucky enough that getting back to sleep again wasn't usually a problem, but the quality of my sleep was consistently poor — confirmed by disappointingly predictable results on every smart watch I've tried. Most noticeably, though, I would nearly always wake up still feeling tired and groggy, with that heavy sense of not having had enough sleep.
Genuinely good nights have been a rare occasion. And even rarer has been that unmistakable feeling of waking up fully restored — refreshed in a way that's hard to explain until you've been without it for a while.
Until very recently.
I started taking magnesium L-threonate when I began stocking it here at Potley's Apothecary. Within a couple of weeks, I noticed something I hadn't expected: I was sleeping deeply. Not just falling asleep faster — actually waking up feeling like I'd genuinely rested. That hasn't happened consistently for years.
So I wanted to share what I've learned about why this form of magnesium is different — and why I think it's worth knowing about, especially if you're a woman in your 40s or navigating perimenopause.
What is magnesium L-threonate?
Magnesium L-threonate is a specific form of magnesium in which the mineral is bound to L-threonic acid — a natural compound derived from vitamin C. It was originally developed through research at MIT and has been studied for one particularly interesting property: its potential ability to cross the blood-brain barrier more effectively than conventional magnesium forms like citrate, oxide, or glycinate.
Most magnesium supplements do an excellent job supporting muscle function, energy production, and hundreds of other bodily processes. But standard forms don't easily reach the brain in significant amounts. Magnesium L-threonate is the only form of magnesium clinically shown to meaningfully raise magnesium levels in the brain, producing a 15% increase in brain magnesium and a 54% increase in cerebrospinal fluid threonate levels in studies.
What are the benefits of magnesium L-threonate?
As a food supplement in the UK, magnesium L-threonate is not a medicine and cannot be used to treat, cure, or prevent any condition. What it can do is support your general health in the same way any quality supplement might. Here's what the research and authorised health claims suggest.
Sleep quality
This is the benefit that gets talked about most — and the one I can personally speak to. A randomised controlled trial published in Sleep Medicine X (2024) found that people taking magnesium L-threonate reported meaningful improvements in sleep quality compared to a placebo group. Not just getting to sleep more easily, but the quality of sleep: less waking in the night, waking up feeling more restored, and better mood and mental alertness during the day.
That matches what I've experienced, and what many of our customers have told us too. The feedback we hear most often is less night waking, a feeling of sleeping more deeply, and waking up actually feeling like you've had a proper sleep rather than just clocking the hours.
Brain health and cognitive support
One of the most striking pieces of research on magnesium L-threonate was published in Frontiers in Nutrition in early 2026. In a randomised, double-blind, placebo-controlled trial of 100 adults, participants taking magnesium L-threonate for just six weeks showed cognitive improvements equivalent to a brain age that was 7.5 years younger than the placebo group — with the greatest gains seen in older participants. A separate 12-week trial focused on adults aged 50 to 70 found an even larger effect, with cognitive age improvements equivalent to approximately nine years. These weren't subjective feelings — they were measured using the NIH Cognitive Toolbox, a standardised neurological assessment tool.
Full study: https://pmc.ncbi.nlm.nih.gov/articles/PMC12832366/
Magnesium for perimenopause and menopause
This is where I think magnesium L-threonate is criminally undertalked about. During perimenopause and menopause, oestrogen levels drop — and oestrogen plays a role in how well the body retains and uses magnesium. So at exactly the time when your body most needs good sleep, emotional balance, and mental clarity, your magnesium status may be quietly declining.
Authorised health claims for magnesium include support for normal psychological function and the normal functioning of the nervous system — both things that can feel like they're under serious pressure during the hormonal upheaval of midlife. Many women in perimenopause describe a cluster of symptoms that magnesium is known to support: broken sleep, low mood, brain fog, anxiety, and fatigue.
The brain-targeted nature of magnesium L-threonate makes it particularly relevant here. When sleep is disrupted by night sweats or hormonal changes, the quality of sleep — not just the quantity — matters enormously. We've had customers come back and tell us it's become a non-negotiable part of their evening routine. Not a dramatic overnight transformation, but a quiet, steady improvement in how they feel — which, when you're in the middle of perimenopause, is everything.
Mood, stress and just feeling more like yourself
One thing that often gets mentioned alongside sleep improvements is mood. They're connected, of course — better sleep leads to better days. But magnesium itself is involved in the production of neurotransmitters, and authorised health claims for magnesium include its role in supporting normal psychological function and reducing tiredness and fatigue. For women in midlife, especially, the low-level anxiety, the feeling of being constantly depleted — this is where magnesium L-threonate is worth trying as part of a thoughtful daily routine.
How does magnesium L-threonate compare to other forms?
Magnesium citrate — widely used, good absorption, popular for digestive support. Doesn't significantly raise brain magnesium levels.
Magnesium glycinate — gentle on the stomach, well absorbed, popular for relaxation and sleep. Also doesn't cross the blood-brain barrier effectively.
Magnesium oxide — cheap, but poorly absorbed. Often used as a laxative rather than a nutritional supplement.
Magnesium L-threonate — specifically formulated for brain bioavailability. More expensive than standard forms, but designed for a different purpose. Best suited to those focused on cognitive support, sleep quality, and healthy ageing.
How to take magnesium L-threonate — our suggestions
Our suggestion for starting out: Even though research doses tend to be around 1,500–2,000mg, I personally found significant improvement with just 500mg — though it's worth noting I'm quite small (160cm, 64kg), so body size may play a role in how much you need. I take it around an hour before bed.
Many people find a split dose works well for them: 500mg in the morning and 1,000mg an hour before bed. Magnesium is known to help activate the parasympathetic nervous system — think of it as the brakes on your autonomic nervous system, the part that helps your body shift out of stress mode and into rest. Taking some during the day can be g helpful if you tend to run on an activated, anxious, or wired nervous system. That said, it can also make some people feel quite sleepy during the day, which is why I personally prefer to take mine at night only.
As with all food supplements, start small, see how it feels, and if you want to make changes, do so gradually. There's no rush — if you've spent years not sleeping well, a gentle, steady improvement is still a transformation. Your body will tell you what it needs.
Each 500mg capsule delivers approximately 37.5mg of elemental magnesium — well within the UK safe upper limit of 400mg elemental magnesium from supplements per day.
As always — if you're pregnant, breastfeeding, have a kidney condition, or take prescription medication, check with your GP before starting anything new.
How does magnesium L-threonate fit into a supplement stack for cognitive health, nervous system support and healthy ageing?
Really well, as it turns out. Here's how I'd think about it.
Morning — Flow and Glow Mushroom Powder
Our Flow and Glow blend combines six functional mushrooms with ashwagandha and rhodiola. Rhodiola for mental stamina and stress resilience, ashwagandha to support a calmer baseline, and Lion's Mane — studied for its role in supporting nerve growth factor and long-term cognitive health. A grounded, focused start to the day.
During the day — Cacao Our cacao collection
Ceremonial cacao — gives you a food-based source of magnesium alongside flavanols and theobromine, a gentler, more sustained alternative to caffeine. A ceremonial cacao in the morning or afternoon is one of the loveliest swaps you can make if you're trying to reduce coffee.
For targeted cognitive support Lion's Mane
We stock both a pure Lion's Mane powder and a dual extract standardised to 10% beta-glucans. If cognitive support and nerve health are your focus, the dual extract is the one to go for — the extraction process concentrates the active compounds in a way that powder alone doesn't achieve.
For energy and resilience
Shilajit with Ashwagandha Rich in fulvic acid and trace minerals, shilajit is a grounding, mineral-rich addition traditionally used to support energy and vitality. Paired with ashwagandha, it's particularly popular with customers who feel depleted or are navigating high-stress periods.
Evening — Magnesium L-Threonate
And then at night, we come back to where we started. Taken an hour or so before bed, to help the nervous system shift into rest, support deep sleep, and give your brain the conditions it needs to consolidate everything the day brought.
Morning clarity. Daytime nourishment. Restful nights.
A note from me
I only stock supplements I genuinely believe in. My dedication to plants and mushrooms runs deep — my relationship with master plants and fungi is a whole other story — so magnesium L-threonate might seem a little out of place at first glance.
But here's why it isn't. As a somatic coach, I believe deeply that we can only truly flow, and fully inhabit our lives and meet all of life where we are at, when our nervous system is working with us. Not against us, not dragging us under — but flexible, resourced, and capable of moving between states as life asks us to. Our nervous system is always doing its best for us, even when it feels like it isn't. The goal was never to stop it activating — it's to have enough in the tank that we can come back to ourselves. And we can't do any of that running on empty.
That's where magnesium L-threonate has earned its place here. Sleep is foundational to everything — to regulation, to resilience, to feeling like yourself. And this is a supplement I've seen make a real difference, starting with myself.
It's become one of those things I recommend to friends and family especially my sisterhood experiencing perimenopause and the general impact of being a women in her 40's living in a system that our bodies were never designed for! The sleep improvement, for me, was real and noticeable. And I've heard enough similar stories since to feel confident saying: if you're not sleeping well, if you're somewhere in the perimenopausal years, or if you just want to feel sharper and more like yourself — this is genuinely worth trying.
This article is for informational purposes only. Food supplements are not intended to diagnose, treat, cure or prevent any disease or health condition. Always consult a healthcare professional if you have a medical condition or take prescription medication.
If my story resonates with you and you want to try Magnesium L-Threonate you can order it here.