Perimenopause Brain Fog: Why You Have Trouble Thinking Clearly

Struggling to concentrate, forgetting words or walking into a room and forgetting why you're there? Perimenopause brain fog is common and can be unsettling, but there are several reasons your thinking may feel different during midlife — and things you can do to support your brain.

Have you ever been in the middle of a conversation and suddenly completely forgotten the word you were looking for?

You know the word. You can almost see it in your mind. You know exactly what you want to say, but somehow it refuses to make its way out of your brain.

Or perhaps you've walked into the kitchen and then stood there wondering why you went in there in the first place. Maybe you've read an email three times and still can't take in what it says, or you've found yourself staring at your computer wondering why a task that would normally take you ten minutes is suddenly taking half an hour.

These moments can be funny when they happen occasionally. During perimenopause, however, they can start to feel much less amusing.

For many women, one of the most unsettling things about this stage of life isn't the hot flushes or the changing periods. It is the feeling that your brain isn't quite working the way it used to.

And if you've always been organised, capable and mentally sharp, that can be surprisingly frightening.

You might start wondering whether you're losing your memory. Whether you're becoming less capable at work. Whether something more serious is happening.

The good news is that changes in concentration, memory and word finding are commonly reported during the menopause transition. They are real experiences, and you're certainly not the only woman wondering what has happened to her brain.

But there is an important point I'd like to make before we blame everything on hormones.

Brain fog isn't caused by one thing.

Your brain is influenced by your hormones, but it is also influenced by sleep, stress, mood, nutrition, movement, medications, alcohol, illness and the sheer amount of information you're trying to process every day.

And when several of those things change at the same time, it isn't surprising that your brain can start to feel a little less reliable.

What exactly is perimenopause brain fog?

“Brain fog” isn't a medical diagnosis. It is a term women commonly use to describe a collection of experiences that can include forgetfulness, difficulty concentrating, trouble finding words, losing your train of thought, feeling mentally slower or struggling to stay focused.

For some women, it is relatively subtle. You might notice that you need to write things down more often or that you don't retain information quite as easily.

For others, it can feel much more significant. You may struggle to concentrate at work, forget conversations you've recently had or find yourself becoming frustrated because you know you're capable of more than your brain seems willing to give you on that particular day.

It is also worth remembering that feeling cognitively different doesn't necessarily mean that your underlying cognitive ability has dramatically declined.

Research into cognition during the menopause transition suggests that some women experience changes in aspects of memory and attention, although these changes are generally subtle and vary considerably between individuals.

In other words, you can genuinely feel as though your brain is different without that meaning you're becoming less intelligent or that you're developing dementia.

That distinction matters because the fear surrounding brain fog can sometimes become worse than the symptom itself.

Can perimenopause really affect your brain?

Yes.

Your brain is not separate from the rest of your hormonal system. Oestrogen has effects throughout the brain, including areas involved in memory, learning, attention and other cognitive processes.

During perimenopause, oestrogen doesn't simply decline gradually. It can fluctuate significantly, sometimes from one cycle to the next.

That changing hormonal environment may contribute to the cognitive changes some women notice during this stage of life.

But this is where the story gets more interesting.

If you're experiencing brain fog, it is tempting to say, “It's my hormones,” and leave it there. Hormones may be part of the explanation, but they aren't necessarily the whole explanation.

Imagine that your hormones are fluctuating, you're waking at 3am, you're carrying an enormous mental load, you're drinking more coffee because you're exhausted and you're trying to function at work while remembering who needs to be where and when.

Of course your brain is going to feel different.

This is why I prefer to look at the whole picture rather than searching for one cause or one magic solution.

Why does poor sleep make brain fog worse?

If there is one connection I want you to understand, it is the relationship between sleep and cognition.

Your brain needs sleep.

During sleep, your brain carries out important processes involved in memory consolidation, learning, emotional regulation and recovery. When you don't get enough good-quality sleep, your ability to concentrate, remember information and regulate your emotions can suffer.

And unfortunately, sleep disruption is incredibly common during perimenopause.

You may struggle to fall asleep, wake repeatedly during the night, wake because you're hot, find yourself lying awake at 3am or simply wake in the morning feeling as though you've barely slept.

Then you get through the day feeling exhausted and wonder why you can't concentrate.

This is one of the reasons I think it is too simplistic to attribute every episode of brain fog directly to declining oestrogen.

Sometimes the pathway looks something like this:

Hormonal changes affect your sleep → poor sleep leaves you exhausted → exhaustion affects concentration and memory → you experience what you describe as brain fog.

Of course, it isn't always that simple, and several things can be happening simultaneously.

But if your sleep is poor, it is absolutely worth addressing rather than simply accepting that brain fog is something you have to put up with.

If you're struggling to stay asleep, have a read of Perimenopause and Sleep: Why You Can't Stay Asleep, and if 3am has become your particularly unwelcome wake-up call, I've also written Why You're Waking Up at 3am in Perimenopause.

Could your mental load be contributing to brain fog?

I think this is one of the most overlooked parts of the conversation.

Women in midlife are often carrying an extraordinary amount.

You might be working, raising teenagers, managing a household, worrying about ageing parents, navigating a relationship, keeping track of everyone's appointments, remembering what needs to be bought, organising holidays, managing finances and trying to maintain some kind of social life at the same time.

Your brain is essentially running a very large number of background programmes all day long.

And then we wonder why we can't concentrate.

There is a difference between having a memory problem and having too much information competing for your attention.

When you're constantly switching between tasks, notifications, conversations, emails and responsibilities, it becomes harder to focus deeply on one thing. Persistent stress can also affect attention and working memory.

This is why sometimes the answer to brain fog isn't another supplement, another productivity system or another thing to add to your morning routine.

Sometimes the answer is to take something away.

If this sounds familiar, I think you'll find The Mental Load of Midlife Women (And Why Perimenopause Can Make It Harder) particularly relevant.

Why can't you find the right word anymore?

This is probably one of the symptoms women find most alarming.

You can picture the person. You know the name. You know the word you're trying to find. It is almost there, but you just can't retrieve it.

Then, five minutes later, it suddenly pops into your head when you are doing something completely unrelated.

Word-finding difficulties can occur during the menopause transition, and again, hormonal changes may be part of the picture. Sleep disruption, stress, anxiety and fatigue can also make these experiences more noticeable.

The important thing is not to interpret every forgotten word as evidence that your cognitive abilities are disappearing.

Your brain has not forgotten how to speak.

Sometimes it simply needs a little longer to retrieve the information.

And honestly, I think we could all benefit from being a little kinder to ourselves when this happens. You don't need to apologise for forgetting a word, and you certainly don't need to panic.

Give yourself a moment.

The word will probably turn up when it's good and ready.

Can what you eat affect brain fog?

This is where I want to be careful, because there is a tendency to turn nutrition into the answer for everything.

There isn't one food that will cure perimenopause brain fog, and I would be very sceptical of anyone promising you otherwise.

Your brain needs energy and a wide variety of nutrients to function properly, so the overall pattern of your diet matters. This is one reason I like to think about crowding in rather than restriction.

Instead of starting with everything you think you shouldn't eat, start by asking yourself what your body needs more of.

More vegetables and fruit.

More legumes and wholegrains.

More nuts and seeds.

Adequate protein.

Sources of healthy fats, including omega-3 fats.

A wide variety of plant foods.

Foods that provide the vitamins, minerals and fibre your body needs.

When you focus on crowding those foods into your day, you often naturally create less room for the foods that aren't particularly nourishing.

And yes, there is still room for cake.

Because a healthy diet doesn't have to be a joyless diet.

What about blood sugar and brain fog?

You've probably heard a lot about blood sugar and brain fog, particularly on social media.

There is some truth behind the idea that what you eat can influence how you feel after a meal, but the story is considerably more complicated than “carbohydrates cause brain fog”.

Your brain relies heavily on glucose for energy, and carbohydrate-containing foods can be a valuable part of a healthy diet. Wholegrains, fruit, legumes and starchy vegetables provide carbohydrate alongside fibre and other nutrients.

The overall composition of your meal matters.

A breakfast consisting largely of refined carbohydrate and little else is likely to provide a different nutritional experience from a breakfast that combines protein, fibre, healthy fats and a source of carbohydrate.

Think about the difference between toast with jam and wholegrain toast with eggs, avocado and vegetables.

Both contain carbohydrate.

But they are very different meals.

So rather than becoming frightened of carbohydrates, I'd encourage you to think about building balanced meals.

This is much more sustainable than trying to eliminate an entire food group because someone on Instagram told you it was responsible for your brain fog.

Does protein help with brain fog?

Protein is incredibly important during midlife, particularly because maintaining muscle becomes increasingly important as we age.

But I wouldn't tell you that eating more protein will magically clear your brain fog.

That isn't supported by the evidence.

Protein provides amino acids that the body uses for many different functions, and including adequate protein in your meals can help with satiety and support muscle maintenance.

Those are very good reasons to include it.

But your brain isn't sitting there waiting for a protein shake to arrive before it will start working properly.

Think about your overall dietary pattern rather than searching for a single nutrient to solve the problem.

If you're interested in how I approach nutrition during perimenopause, have a look at What to Eat During Perimenopause, where I explain my crowding-in approach in more detail.

Could iron deficiency be contributing to your brain fog?

This is one that I don't want women to overlook, particularly if your periods have become heavier.

Perimenopause can bring changes in menstrual bleeding, and some women experience significantly heavier periods. Heavy menstrual bleeding can increase the risk of iron deficiency.

Iron is essential for transporting oxygen around the body, and iron deficiency can contribute to fatigue and difficulties with concentration.

So if you're exhausted, struggling to think clearly and your periods have become much heavier, don't simply assume that everything is hormonal.

It's worth talking to your GP about whether your iron status should be checked.

This is a good example of why I am always reluctant to tell women that every symptom they experience in their 40s and 50s is “just perimenopause”.

Sometimes it is.

Sometimes there is something else worth investigating.

What about your thyroid, B12 and other health conditions?

There are many possible causes of fatigue and cognitive difficulties, including thyroid disorders, nutritional deficiencies, medication effects, anxiety, depression, sleep disorders and other medical conditions.

This doesn't mean you need to panic every time you forget your keys.

Most of us do that.

But if your symptoms are persistent, worsening or interfering with your ability to work or manage everyday life, it's worth speaking with your GP.

And if you experience significant confusion, difficulty carrying out familiar tasks, getting lost in familiar places or a sudden and dramatic change in your cognitive function, seek medical attention rather than assuming it is perimenopause.

Perimenopause is common, but it isn't an explanation for everything.

Can exercise help your brain?

Absolutely, and this is one of the reasons I encourage women to think about movement as part of their overall health rather than simply a tool for weight loss.

Regular physical activity supports cardiovascular health, and cardiovascular health and brain health are closely connected. Exercise is also associated with benefits for mood, sleep and overall physical function.

Resistance training has an important role too. It helps maintain muscle and strength, supports physical independence and forms part of a healthy ageing strategy.

You don't have to become a gym person overnight.

A brisk walk, a strength session, swimming, cycling, dancing or simply becoming more active during your day all count.

The best form of exercise is the one that you can actually sustain.

If you're interested in why I think strength training becomes particularly important in midlife, read Why You Need to Get Stronger During Perimenopause, Not Just Exercise More.

What if you're simply exhausted?

This sounds almost too obvious, but I think it is worth saying.

Sometimes brain fog is just what an exhausted brain looks like.

If you're sleeping badly, working long hours, caring for other people, constantly multitasking and rarely getting a genuine opportunity to recover, your brain is going to struggle.

You don't need to be more disciplined.

You might need to rest.

And I know that can be a difficult message for women to hear because rest can feel like something we need to earn.

But your brain isn't designed to operate at maximum capacity from the moment you wake up until you fall into bed.

Sometimes putting your phone away, eating lunch away from your computer, taking a walk without listening to anything and giving yourself ten quiet minutes can do more for your mental clarity than another productivity hack.

What can you actually do about perimenopause brain fog?

There isn't a single brain-fog protocol that works for every woman, but there are some foundations that are worth getting right.

Start with sleep. If you're consistently waking during the night or struggling to get enough restorative sleep, don't simply accept it as an inevitable part of getting older. There may be things you can address.

Look at your mental load. If your brain is carrying everyone's appointments, problems, schedules and responsibilities, consider what can be delegated, simplified or removed.

Eat well rather than perfectly. Focus on adequate protein, plenty of fibre, a wide variety of plant foods, healthy fats and nutrient-dense meals.

Move regularly. Combine strength training with cardiovascular activity and plenty of everyday movement.

Give your brain some quiet. Constant stimulation isn't the same thing as productivity.

Check for other causes. If symptoms are persistent or concerning, talk to your GP about whether iron deficiency, thyroid issues, medication, mood or sleep disorders could be contributing.

And finally, don't spend a fortune chasing supplements that promise to make you feel like a completely different woman.

Start with the boring stuff.

It works surprisingly well.

What about HRT and brain fog?

This is another area where the conversation can become unnecessarily black and white.

Menopausal hormone therapy can be an appropriate treatment for some women experiencing troublesome menopausal symptoms, and some women report improvements in their cognitive symptoms when their other symptoms, particularly sleep disruption and vasomotor symptoms, improve.

However, HRT isn't a guaranteed treatment for brain fog, nor should it be presented as a universal way to prevent cognitive decline.

Whether it is appropriate for you depends on your individual symptoms, medical history, risk factors and preferences.

If your perimenopause symptoms are affecting your quality of life, it is worth having a conversation with a GP or menopause-informed healthcare professional about the options available to you.

You don't have to make that decision based on something you saw on social media.

The part of brain fog nobody talks about

I think one of the reasons brain fog feels so upsetting is because your brain is part of your identity.

If you've spent your life being the organised one, the capable one, the woman who remembers everyone's birthdays and always knows what needs to happen next, suddenly forgetting the name of someone you've known for ten years can feel like a much bigger deal than it actually is.

You may start questioning yourself.

Am I losing my ability to do my job?

Am I becoming less capable?

What if this gets worse?

And when you're already experiencing other changes in midlife — perhaps your body feels unfamiliar, your sleep has changed and you're questioning what you want from the next stage of your life — brain fog can feel like one more thing you no longer recognise.

But you haven't suddenly become less intelligent.

You haven't lost the decades of knowledge and experience you've built.

You are still you.

Your brain is simply moving through a period of change.

You don't need to optimise your brain. You need to support it.

I think we have become obsessed with optimisation.

There is a supplement for memory, a powder for focus, a morning routine for productivity and a “hack” for almost every bodily function.

But your brain isn't a machine that needs to be optimised every minute of every day.

It is part of your body.

It needs adequate nutrition, movement, sleep and recovery. It needs connection and stimulation, but it also needs periods of quiet.

And sometimes it needs you to stop expecting quite so much from it.

Perhaps the goal isn't to become the woman who can remember every name, answer every email and juggle twelve things simultaneously.

Perhaps the goal is to create the conditions in which your brain can do what it does best.

Your brain isn't failing you

Perimenopause can make you feel as though your body is changing in ways you didn't ask for.

Your sleep may be different. Your energy may be different. Your body may be changing. Your emotions may feel different.

And then your brain seems to join the party.

But brain fog doesn't mean that your best years are behind you.

It doesn't mean you're becoming less capable.

And it certainly doesn't mean you need to panic every time a word temporarily disappears.

Your hormones may be part of the picture, but so are sleep, stress, nutrition, movement and the extraordinary mental load that many women carry through midlife.

So instead of asking:

“How do I get rid of brain fog?”

perhaps ask:

“What is my brain asking for?”

More sleep?

More recovery?

Better nourishment?

More movement?

Less mental load?

A medical check-up?

Maybe.

And that's a much more useful place to start.

Not sure where to start?

Brain fog rarely exists in isolation.

It can sit alongside exhaustion, disrupted sleep, changes in your body, stress and changes in the way you're eating and moving.

That's why I've created the free Perimenopause Snapshot Assessment.

It looks at five foundations — energy, nutrition, movement, sleep and stress — and helps you identify where you may need the most support right now.

You don't need to overhaul your entire life. You just need to know where to start.

Take the free Perimenopause Snapshot Assessment →

Frequently Asked Questions

Is brain fog a symptom of perimenopause?

Yes. Difficulty concentrating, forgetfulness and word-finding difficulties are commonly reported during the menopause transition. Cognitive changes vary between women and can also be influenced by sleep, stress, mood, medications and other health factors.

What does perimenopause brain fog feel like?

Brain fog can involve difficulty concentrating, forgetting information, losing your train of thought, struggling to find words or feeling mentally slower than usual. These experiences are common during midlife, although they can have several contributing causes.

Can perimenopause cause memory problems?

Some women experience changes in memory during perimenopause, and research suggests that certain aspects of cognition may change during the menopause transition. However, occasional forgetfulness is not the same as significant cognitive impairment or dementia.

Why can't I remember words during perimenopause?

Word-finding difficulties can occur during the menopause transition. Hormonal changes may contribute, while poor sleep, stress, anxiety and fatigue can make these experiences more noticeable.

Can poor sleep cause brain fog?

Yes. Poor sleep can affect concentration, attention, working memory and mood. Because sleep disruption is common during perimenopause, improving sleep can be an important part of supporting cognitive function.

Does stress cause brain fog?

Persistent stress can affect concentration and working memory. The mental load of midlife can also leave you with less cognitive capacity available for focused attention, particularly when you're already tired or sleeping poorly.

What should I eat for perimenopause brain fog?

There is no single food that cures brain fog. A varied, nutrient-rich eating pattern that includes adequate protein, fibre, vegetables, fruit, wholegrains, healthy fats and a wide range of plant foods is a sensible foundation for overall health and brain health.

Should I avoid carbohydrates if I have brain fog?

No. Carbohydrates can be part of a healthy diet and provide energy, fibre and important nutrients. Rather than eliminating them, focus on the overall meal and combine carbohydrate foods with protein, fibre and healthy fats.

Can exercise help with perimenopause brain fog?

Regular physical activity supports cardiovascular health, mood and overall brain health. Combining aerobic exercise, resistance training and everyday movement can be an important part of a healthy lifestyle during midlife.

Do supplements help with perimenopause brain fog?

There is no universal supplement that has been shown to eliminate perimenopause brain fog. Supplements may be useful when a specific deficiency or clinical need is identified, but they shouldn't replace good nutrition, sleep, movement or appropriate medical care.

Could iron deficiency be causing my brain fog?

It can contribute to fatigue and difficulties with concentration, particularly if you have heavy menstrual bleeding. If your periods have become significantly heavier and you're experiencing persistent fatigue or cognitive difficulties, speak with your GP about whether your iron status should be assessed.

When should I see a doctor about brain fog?

Talk with your GP if cognitive symptoms are persistent, worsening or interfering with your work or daily life. It is important to consider other potential causes, including iron deficiency, thyroid problems, medication effects, anxiety, depression and sleep disorders, rather than automatically attributing everything to perimenopause.

About Louise

Louise is a nutritionist specialising in women’s nutrition and lifestyle during perimenopause and midlife. Through her programmes, she helps women understand the changes happening in their bodies and build practical nutrition and lifestyle strategies to feel more energised, rested and confident through this stage of life.

Last updated: August 2026