I spent 22 years working with menopausal women. I was asked to stop talking about the 3am shield.

I started paying attention to this because of my mother.

At 51 she became someone else. Three hours of sleep a night. Crying at the kitchen sink and unable to say why. My father thought it was depression. Her GP thought it was anxiety. She lived like that for nine years.

Nine years. And the thing she said most wasn't about the heat, or the sweating. It was: I've disappeared.

When a colleague first told me you could work on this through the skin, and overnight, I laughed at her.

Twenty-two years on the ward. I knew what was on the menu: hormones, or get on with it. I assumed it was another internet thing sold to desperate women.

It took me seven months to try it.

Here's what nobody explains properly.

The heat isn't the cause. The heat is a symptom.

For thirty years your oestrogen did a quiet job on your behalf: it kept cortisol — your stress hormone — on a leash and on a schedule. Cortisol is meant to rise in the morning to get you up, and fall at night to let you sleep.

When oestrogen drops, that leash snaps.

Cortisol starts climbing at the wrong hour. Around 3am. Before any hot flush, before any bad dream: it climbs, your body reads it as danger, and it wakes you with your heart going.

It's the same thread running through all of it — the middle that won't shift, the short fuse, the anxiety out of nowhere, the tiredness that sleep doesn't touch.

It was never willpower. It was a hormone off its leash, in the middle of the night.

And this is the part that made me angry.

None of this is secret. It's in the literature. And still a woman walks in, says 3am and brain fog, and walks out eleven minutes later with one of two sentences: 'It's your age.' or 'Let's look at HRT.'

HRT is a legitimate choice and for many women it's the right one — I'm not here to argue against it. The problem is it being the only door. Between 'put up with it' and 'hormones' there's an enormous gap, and millions of us are standing in it.

That gap is where my mother spent nine years.

What my colleague showed me I now call the 3am shield.

The logic is almost annoying in how simple it is: if the problem happens while you're asleep, the support has to be working while you're asleep.

Not at 8am. Not once you're already awake. It has to already be there — across the whole night, at the exact hour the leash snaps.

And the main ingredient isn't exotic or expensive. It's magnesium — the one every woman in perimenopause has already heard of, and one of the most studied minerals there is for a calm stress response and sleep.

The difference isn't the what. It's the when, and the how it gets in.

That's when I understood why magnesium tablets never fixed this for anyone.

You take it in the morning with the coffee and it's gone by evening. Or you take it at bedtime and your stomach lets you know. Or you simply forget by the third night, like everyone forgets.

A capsule is a spike and a drop. And your problem isn't a spike. It's a seven-hour window with nobody on watch.

I tried it on myself before I said a word to any patient. Fifty-three, waking at 3:10 with the reliability of an alarm clock, for two years.

The fourth night. Not the first — be suspicious of anyone promising you the first.

I woke at 6:20 and sat on the edge of the bed trying to work out what was wrong. It took me a moment to realise what it was: nothing was wrong. I'd slept through.

I cried in the bathroom so I wouldn't wake my husband.

Five weeks later it was my daughter who said something, not me.

'Mum, you've started laughing at my rubbish jokes again.'

I hadn't noticed I'd stopped.