8 Reasons For Brain Fog and How to Clear It

Have you been halfway through a sentence, and the word just disappears? You walk into a room and forget why you're there. You read the same paragraph three times and still cannot tell anyone what it said.

This isn't normal tiredness.

You've been to your GP. They ordered blood tests, including thyroid and blood sugar, as well as the basics. Everything came back normal. But you know something is off. Your brain just doesn't work the way it used to.

So what exactly is happening? And why did those tests not show it?

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What Is Brain Fog?

Brain fog isn't a medical diagnosis, which is partly why your GP's tests may have come back within normal ranges. It is a symptom of something disrupting your brain's function.

It feels like your mind is clouded. Everything takes longer. Decisions feel harder. Conversations require more effort than they should.

Common experiences include:

• Forgetting words mid-conversation
• Reading something multiple times without it sticking
• Walking into rooms and forgetting why
• Struggling to concentrate on tasks
• Memory problems, even with recent conversations
• Feeling mentally exhausted even after quality sleep

These cognitive symptoms affect how you function in daily life. Brain fog can interfere with work, relationships, and basic tasks that used to feel automatic.

The important thing is that this is a symptom, not a condition. Something is disrupting your cognitive function. Your job is to figure out what. Most standard tests check 10 to 15 markers to look for established disease, not the subtle imbalances that can cause symptoms like these.

At Everlab, we test over 100 markers to help identify what may be disrupting your cognitive function. From nutrient deficiencies and hormonal imbalances to inflammation and metabolic issues that standard testing might not prioritise.

What Brain Fog Feels Like

People describe brain fog differently, but certain patterns show up consistently.

• The Mental Cloud - Your mind feels tired in a way sleep does not fix. There is a barrier between you and clear thought. Ideas do not flow the way they used to.
• Memory Gaps - You forget what someone just told you. Names slip away. Mental clarity seems impossible to achieve.
• Slow Processing - Everything takes longer than it should. Simple decisions feel hard. Problem-solving exhausts you. You cannot find the right words when you need them.

Brain fog symptoms vary from person to person and change throughout the day. Many people  experience brain fog more intensely in the afternoon or during particularly stressful periods.

This can be frustrating because of how it affects every aspect of your life. At home, you forget important conversations. In meetings, you struggle to focus. Socially, you zone out. The mental fatigue becomes its own burden.

Over time, this can chip away at your confidence. Many people develop anxiety or a low mood simply from the frustration of not being able to think clearly.

Causes of Brain Fog?

Brain fog happens when something disrupts how your brain normally works. Here are the most common underlying causes:

1. Sleep Problems

Your brain needs quality sleep to function properly. During sleep, it consolidates memories, clears waste products, and repairs damage from the day.

When sleep is disrupted, whether from insomnia, sleep apnoea, or poor sleep habits, your brain does not get the maintenance it needs. Chronic sleep deprivation can prevent your brain from repairing neural pathways, directly contributing to brain fog.

Even if you are in bed for eight hours, poor sleep quality means your brain is not getting proper rest. Many people have sleep apnoea without realising it, waking repeatedly throughout the night but not remembering.

Consistently getting 7 to 9 hours of quality sleep per night helps ensure your brain is refreshed.

2. Constant Stress

When you are stressed, your body produces cortisol to help you deal with threats. This is useful in the short term, but when stress never lets up, cortisol stays elevated.

Chronic stress and high cortisol may negatively impact brain health, interfering with memory formation and recall. It can block the processes your brain uses to create and access memories, making it harder to focus.

Over time, constant stress can actually change how your brain functions.

This creates another cycle:

• Stress makes thinking harder
• Tasks take longer and feel overwhelming
• Feeling overwhelmed creates more stress

Learning to manage stress through techniques such as deep breathing exercises or meditation can help improve cognitive function.

3. Nutritional Deficiencies

Your brain is an organ that needs specific nutrients to work properly. When these are low, your cognitive performance may suffer.

a). Vitamin B12

B12 helps your brain make the chemicals it uses to send signals. Tests usually flag B12 as a problem only when it is severely low (below 200). This misses the borderline cases. People often experience brain fog when B12 is below 400, still considered "normal" by standard testing.

b). Vitamin D

Nearly one in four Australians is vitamin D deficient, which affects neurotransmitter production. Low levels are linked to poor concentration.

c). Magnesium

Magnesium is involved in over 300 reactions, including nerve transmission at the cellular level. Deficiency may contribute to brain fog, anxiety, and poor sleep.

d). Iron

You can have normal haemoglobin but low iron stores (ferritin). This affects how oxygen is delivered to your brain. causing fatigue and cognitive dysfunction. Iron storage below 70 is often problematic, even though the "normal" range goes down to 15.

e). Omega-3 Fatty Acids

About 60% of your brain is fat. A diet rich in omega-3 fatty acids can protect brain function and slow cognitive dysfunction. Low levels are linked to cognitive impairment.

4. Blood Sugar Instability

Your brain runs almost entirely on glucose. When blood sugar is stable, brain function is normal. When it crashes or spikes dramatically, your brain struggles to cope.

Here's how it happens:

You eat certain foods high in sugar or refined carbs → Your blood sugar levels spike → Your body produces insulin to bring it down → The insulin works too well, and blood sugar crashes.

Low blood sugar levels during the crash mean your brain doesn't have enough fuel. That's when brain fog hits.

Here's a guide to fasting insulin.

5. Hormonal Changes and Imbalances

Hormones control how your brain makes and uses the chemicals it needs for cognitive function.

a). Menopause and Oestrogen

During menopause, oestrogen drops significantly. Oestrogen helps your brain make chemicals critical for forming memories. Less oestrogen means less of those chemicals. The result is often called "meno-fog", a difficulty in remembering things and thinking clearly. Hot flashes and other symptoms add to the cognitive burden.

b). Thyroid Issues

Thyroid hormones affect your brain's metabolism. Both hypothyroidism (too little) and hyperthyroidism (too much) are associated with cognitive difficulties.

c). Pregnancy and Postpartum

Hormonal changes during pregnancy can contribute to brain fog. Massive hormonal swings directly affect brain chemistry. This is not just about being tired: the hormones themselves change how you process information.

d). Testosterone

Testosterone affects memory and cognitive function in both men and women. Low levels are linked with difficulty concentrating and mental fatigue.

6. Inflammation

When your body is fighting a viral infection, injury or chronic stress, it releases inflammatory chemicals to help deal with the threat. This is useful short term.

If inflammation becomes constant and low-level, these chemicals can circulate in your central nervous system and interfere with how brain cells communicate. Hence, they interfere with how your brain cells communicate.

Visceral belly fat is particularly problematic. Unlike fat stored elsewhere, organ fat actively releases inflammatory chemicals that can reach your brain and disrupt normal function.

7. Underlying Medical Conditions

Several conditions cause brain fog, often before other symptoms become too obvious:

a). Long COVID

Brain fog is commonly reported after COVID-19 infections, and it can persist for months or even years. COVID-19 can alter the gut microbiome, potentially reducing serotonin production and leading to brain fog. Getting vaccinated against COVID-19 may lower the risk of developing brain fog associated with long COVID.

b). Chronic Fatigue Syndrome

Brain fog is a common symptom in chronic fatigue syndrome (CFS), where cognitive difficulties are prevalent. The condition is characterised by severe exhaustion and brain fog.

c). Fibromyalgia

Fibromyalgia causes "fibro-fog" alongside chronic pain. Both pain and inflammation contribute to thinking difficulties.

d). Autoimmune Disorders

Conditions like lupus and multiple sclerosis (MS) can cause brain fog through immune system dysfunction. Notably, brain fog can start before the condition is obvious enough to diagnose.

e). Depression and Anxiety

Depression and anxiety are mental health conditions that directly affect how your brain processes information. These conditions make it harder to focus, remember things, and think clearly. It works both ways: brain fog makes mood worse, and poor mood makes brain fog worse.

f). ADHD

Attention deficit hyperactivity disorder (ADHD) symptoms often overlap with brain fog, especially regarding focus and memory.

8. Medications and Treatments

Certain medications may cause brain fog as a side effect:

• Some antidepressants
• Allergy medications that make you drowsy
• Sleep aids
• Blood pressure medications
• Pain medications
• Chemotherapy - Patients undergoing chemotherapy often experience "chemo brain," which can affect memory, language use, and executive function

If you suspect your medication is a cause for brain fog, consult your healthcare provider before making any changes.

How to Clear Brain Fog

For many people, brain fog can be improved once the underlying cause is addressed.

1. Prioritise Sleep

Sleep isn't optional for brain function. During sleep, your brain consolidates memories, clears metabolic waste, and repairs damage.

What works:

• Build a consistent bedtime routine
• Keep your bedroom cool (around 18°C), dark, and quiet
• Avoid screens one hour before bed since blue light suppresses sleep hormones
• Cut off caffeine after 2 pm. It stays in your system for 5-6 hours
• Aim for 7-9 hours per night

If you're doing everything right and still sleeping poorly, you might have an undiagnosed sleep disorder.

2. Manage Your Stress

Constant stress keeps cortisol high, which directly blocks memory and focus.

What works:

• Regular exercise, even 30-minute walks help
• Meditation or deep breathing
• Address the source of stress when possible, not just the symptoms

Find practices that actually reduce your stress load, not just distract from it.

3. Stabilise Your Blood Sugar

If you experience afternoon crashes or can't focus after meals, blood sugar is likely involved.

What works:

• Don't skip meals - This causes blood sugar drops that directly impair brain function
• Eat regularly - Aim for balanced meals every 3-4 hours
• Include protein and fat with every meal to slow glucose absorption
• Try meal sequencing - Eat vegetables and protein before carbohydrates  

Diet can play a role in brain fog, particularly if there are food allergies or sensitivities.

4. Move Your Body

Exercise increases blood flow to your brain and may help improve mood, sleep, and cognitive function. Engaging in 150 minutes of moderate aerobic exercise per week can increase blood flow to the brain and improve symptoms of brain fog.

Regular physical activity:

• Reduces brain inflammation
• Improves sleep quality
• Lowers stress hormones
• Supports overall brain health

Consistent moderate activity works best: walking, swimming, cycling. Nothing extreme is needed.

5. Eat for Brain Health

Your brain needs proper fuel. Eating nutritious foods with antioxidants and omega-3s can help alleviate brain fog symptoms.

Understanding how nutrition affects long-term health helps put daily food choices into perspective.

A balanced diet rich in omega-3 fatty acids, B vitamins, and other key nutrients can protect brain function. Focus on:

• Fatty fish rich in omega-3s (salmon, sardines, mackerel)
• Colourful vegetables and berries for antioxidants
• Whole grains for steady energy
• Nuts, seeds, and healthy fats
• Adequate fibre for gut health

Avoid blood sugar spikes from processed foods and excessive sugar.

6. Stay Hydrated

Even mild dehydration affects your ability to think clearly. Aim for adequate water intake throughout the day.

7. Take Strategic Breaks

Your focus naturally drops after 45 to 90 minutes of sustained concentration. Taking short breaks throughout the day can help avoid overworking your brain and manage brain fog.

What works:

• Do one thing at a time - Trying to multitask makes mental fatigue worse
• Take 5-minute breaks every hour or so- Regular breaks help to maintain mental clarity
• Write important things down instead of trying to remember everything
• Create simple routines for things you do regularly to save mental energy

8. Use External Memory Aids

While you're addressing the root cause, these practical approaches can help manage forgetfulness associated with brain fog:

• Write things down immediately rather than trying to remember them
• Use calendars, reminders, and planners
• Create systems for things you do regularly
• Keep important items in the same place

These aren't crutches. They're smart ways to work with your current capacity while you address the underlying issues.

When to Seek Help

Some symptoms of brain fog clear up with lifestyle changes. However, if you have tried these changes and you are still struggling, it's time to dig deeper.

See a healthcare provider if:

• Brain fog symptoms have lasted more than a few weeks
• They're getting worse over time
• They're significantly interfering with work, school, or daily tasks
• You have other symptoms (unexplained weight changes, extreme fatigue, mood changes)
• Symptoms started after a viral infection or a new medication

Why Standard Testing Often Misses the Cause

Standard tests are designed to catch disease, not optimise health. You can feel awful but still fall "in range," because the "normal" ranges are really wide.

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Single numbers also miss patterns. Your results might show:

• Iron storage: low-normal
• Vitamin D: borderline
• Insulin: slightly elevated
• Inflammation: creeping up

Individually, these numbers might not trigger a red flag, but together they may explain your symptoms.

Comprehensive Testing and Finding the Root Cause

When standard testing doesn't show anything, a more comprehensive approach will often find the answer.

The difference is in what gets measured and how it's interpreted.

• Instead of checking 10-15 markers to rule out disease, comprehensive testing examines how your body is actually functioning, catching imbalances before they become serious health issues.
• Instead of just checking fasting blood sugar, continuous glucose monitoring shows what happens after you eat. Many individuals have normal morning numbers but huge spikes throughout the day that cause brain fog.
• Instead of checking whether iron is "normal," detailed testing specifically checks iron storage. The difference between storage at 30 (technically fine) and 70 (where most people feel sharp) is often the difference between brain fog and mental clarity.
• Metabolic changes often show up as cognitive symptoms first. Issues with how cells make energy, insulin resistance, and ongoing inflammation. These appear as mental fog before they become obvious diseases.

What Do Comprehensive Health Assessments Include?

Everlab's Health Check Plan goes beyond standard testing to identify what's disrupting your cognitive function:

a. Advanced Blood Testing:

• Detailed metabolic markers, including glucose, insulin, and markers of insulin resistance
• Complete lipid profiles and cardiovascular health markers
• Inflammation markers that standard tests skip
• Thyroid function testing
• Nutrient levels, including markers often missed in standard panels
• Hormone assessment

b. Advanced Testing:

• DEXA body composition scan - Shows metabolic health through body composition, muscle mass, and fat distribution, including visceral fat
• Blood pressure and cardiovascular assessment
• Continuous glucose monitoring is available to track blood sugar patterns throughout the day

c. Expert Analysis

Results are reviewed by Everlab doctors who explain what each marker means for your brain function, specifically, not just whether you have a disease. You get a clear understanding of which markers are off, why that matters for how you feel, and what to do about it.

Book your comprehensive health check with Everlab and find out what's really causing your brain fog.

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Conclusion

Although brain fog is frustrating, it is rarely permanent. It's your body telling you something needs attention.

Sometimes the fix is straightforward, like addressing a nutrient deficiency, stabilising blood sugar, and improving sleep quality. Other times, it requires a deeper investigation into hormonal imbalances, inflammation, or an underlying condition.

The key is identifying what's actually causing your cognitive symptoms rather than just accepting "everything's normal" when you know it's not.

Standard testing is a good starting point. When it doesn't give you answers, and you know something's wrong, comprehensive testing can reveal what basic panels miss.

Sources

1. Cleveland Clinic. (2022). Brain Fog: What It Is, Causes, Symptoms & Treatment
2. American Brain Foundation. Brain Fog: Symptoms and Causes
3. National Institute of Mental Health. Mental Health and Cognitive Function
4. National Cancer Institute. Chemo Brain (Cognitive Impairment)