Perimenopause Brain Fog: Why You Can’t Remember Anything Right Now

Can’t remember what you walked into the room for? Losing your train of thought mid-sentence? Feel like your brain has 17 tabs open and nothing’s loading? That’s not just “mom brain”, it might be perimenopause brain fog, and yes, there’s something you can do about it.

July 30, 2025

“I swear I’m not dumb. My brain just isn’t... braining.”

You used to be sharp. Efficient. On top of it. Who needs a calendar when your memory’s got your back?

Now?

• You’re forgetting basic words

• You re-read the same sentence five times

• You can’t remember what day it is without checking your phone

• You walk into a room and forget why you’re there

It’s not early-onset dementia.

But it might be perimenopause brain fog. And it’s a real, physiological thing.

As a functional dietitian who works with moms in perimenopause every day, I see this exact thing all the time. The good news? There are clear reasons behind it, and even better, ways to feel like yourself again.

Ok remind me, what is perimenopause again?

Perimenopause is the 5–10+ year lead-up to menopause, where your hormones start shifting (read: spiraling) and each cell in your body is impacted.

It can start as early as your mid-30s (yes, really!)

Peri and menopause aren’t just about hot flashes.

Estrogen, progesterone and even testosterone impact your brain, metabolism, your energy, your sleep, and your memory. So things can get weird before you even miss a period.

So why is my brain mush?

Let’s break it down. Brain fog in perimenopause is usually caused by a combo of the following:

1. Estrogen Fluctuations

Estrogen helps regulate:

• Acetylcholine, the brain chemical responsible for memory. This is the same guy responsible for a pep in your step after drinking coffee.

• Serotonin + dopamine, which affect mood and focus

• Glucose uptake in the brain (aka, fuel)

When estrogen goes up and down like a hormonal trampoline in perimenopause, your brain gets glitchy.

2. Low Progesterone = No Chill

Progesterone is your calming hormone. When it’s low (which is common in your late 30s/40s), you get:

• More anxiety

• More insomnia

• Less mental clarity

Low progesterone is linked to problems with word finding and memory, so that’s why you can’t ever remember the name of that one flower (PLUMERIA 🌺 Got it this time!)

3. Chronic Stress & Cortisol Overload

Stress burns through nutrients. It also messes with your sleep, your blood sugar, and your short-term memory.

Fun fact: cortisol literally shrinks the part of your brain responsible for memory if it's elevated for too long. Thanks, motherhood!

Read Next:

From Poop to Peace of Mind: How Gut Health Impacts Mom’s Mental Health

4. Nutrient Depletion

Most moms I work with are low in:

• B vitamins (needed for neurotransmitters and brain function)

• Omega-3s (anti-inflammatory and essential for brain health)

• Magnesium (for calm and clarity)

• Iron (low iron = low oxygen to the brain)

This is especially common postpartum and in women who’ve had multiple pregnancies.

5. Sleep deprivation

If you’re not sleeping deeply, your brain isn’t clearing out the metabolic trash that builds up during the day. That trash → brain fog.

And perimenopause is a jerk to your sleep, thanks to:

• Cortisol surges at 3am

• Night sweats

• Racing thoughts

• Needing to wake up your kids on the weekdays but they absolutely will not sleep in past 6:30am on Saturdays. Just me?

What does perimenopause brain fog feel like?

Losing your train of thought while talking

• Forgetting names, words, or why you walked into a room

• Trouble focusing on work or conversations

• Needing 4 cups of coffee to “turn on”

• Feeling mentally slow or overwhelmed by simple tasks

• That “I know I know this, but it’s just not coming” feeling

You’re not losing your mind. Your brain’s just asking for help.

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So what can you do about it?

🥦 1. Eat to fuel your brain

Blood sugar crashes = brain crashes. So does under-eating.

Support mental clarity by:

• Protein at every meal (aim for 100g/day)

• Healthy fats (avocados, fish, olive oil, nuts)

• Whole food carbs for slow, sustained energy

• Anti-inflammatory foods like berries, leafy greens, and cruciferous veggies

🧠 2. Targeted nutrients that actually help

• B-complex (especially B6, B12, and folate)

• Omega-3s (DHA + EPA) : think fatty fish or a high-quality fish oil

• Magnesium : for calm, sleep, and better stress response

• Iron, if low get your ferritin checked!

These are the building blocks of brain function. Without them, your neurotransmitters can’t do their jobs.

😴 3. Support your sleep

You need deep, restorative sleep to clear brain fog.

Try:

• Magnesium glycinate before bed

• Avoiding caffeine after 1pm

• Blood sugar balance (so you don’t wake at 3am)

• Stress reduction: breathing, walking, therapy, or just hiding in the bathroom for 10 minutes

🧪 4. Get your hormones checked

Low progesterone, wild estrogen swings, and thyroid dysfunction all show up as brain fog before anything else. Don’t let “your labs are normal” be the end of the conversation.

Yes, I can order these for you if we work together.

Read More on the Blog:

What to do when your Labs are “normal,” but you still feel like trash

Bottom Line

If you feel like your brain just… doesn’t work like it used to, you’re not imagining it.

You’re not “just getting older.”

You’re likely dealing with real, fixable imbalances.

Let’s support your brain with food, nutrients, and tools that actually work—so you can feel like yourself again.

📩 Need help figuring out what’s driving your fog?

Let’s work together to test your hormones, replenish your brain, and get your clarity back. Work with me.

xo

Alison

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