Journal #43. Brain Fog and Mental Fatigue.

Brain Fog and Mental Fatigue: What May Be Behind It — and How to Support Clearer Thinking

Most people know the feeling.

You are physically present, but mentally slower than usual. You lose your train of thought, struggle to concentrate, forget small details or feel as though your mind is working through a layer of fog.

Brain fog and mental fatigue are not medical diagnoses on their own. They are common descriptions for a set of symptoms that can affect focus, memory, decision-making and mental energy.

They can be frustrating, especially when work, family and everyday responsibilities still require you to perform.

The useful starting point is not to push through harder. It is to understand what may be contributing.

What do brain fog and mental fatigue feel like?

Brain fog can show up as:

• Difficulty concentrating or staying on task
• Forgetting words, names or why you entered a room
• Slower thinking or decision-making
• Feeling mentally scattered
• Reduced motivation or creative energy
• Struggling to retain information
• Feeling tired even after a reasonable night’s sleep

Mental fatigue is the sense that your brain has simply run out of capacity. You may still be able to get through the day, but everything takes more effort.

These experiences are common, but they should not be ignored if they are persistent, worsening or affecting daily life.

Common contributors to brain fog

There is rarely one single cause. Brain fog and mental fatigue often reflect a combination of lifestyle, health and environmental factors.

Sleep quality

Sleep is when the brain processes information, regulates emotion and carries out important restorative work. Poor sleep quality, irregular sleep patterns or insufficient sleep can quickly affect concentration, mood and mental clarity.

Chronic stress

When the nervous system stays in a state of high alert, it becomes harder to focus, regulate emotions and think clearly. Stress can also affect sleep, appetite, energy and the ability to switch off.

Nutrition and hydration

Irregular meals, low protein intake, dehydration, large blood-sugar swings and diets low in whole foods can all affect energy and concentration.

Nutrient deficiencies can also contribute. Iron, vitamin B12, folate, vitamin D and thyroid function are among the factors a clinician may consider when fatigue or cognitive symptoms persist.

Hormonal changes

Hormonal shifts can affect cognition, mood and energy. This can occur across different life stages and may include menstrual-cycle changes, pregnancy, postpartum recovery, perimenopause, menopause, thyroid conditions and changes in testosterone.

Illness, medication and other health conditions

Brain fog can also follow viral illness, occur alongside chronic pain or mood disorders, or be related to medications and other health conditions. If symptoms are new, persistent or significant, it is worth speaking with a GP rather than self-diagnosing.

Where flavonoids fit

Flavonoids are naturally occurring plant compounds found in foods such as berries, citrus fruit, tea, cocoa, herbs, apples and leafy vegetables.

They are being studied for their antioxidant, vascular and cell-signalling effects. Some research suggests that diets rich in flavonoid-containing foods may support aspects of cognitive function and healthy ageing.

That is encouraging, but it is important to keep the claims proportionate. Flavonoids are not a proven cure for brain fog or mental fatigue, and they should not replace medical assessment when symptoms are ongoing.

They are best viewed as one useful part of a broader pattern of brain-supportive nutrition.

Add more flavonoid-rich foods to your day

A practical approach is to include a wider range of colourful plant foods across the week.

• Berries: blueberries, strawberries, raspberries and blackberries
• Citrus: oranges, mandarins, grapefruit and lemons
• Tea: green and black tea
• Cocoa: dark chocolate with a high cocoa content
• Herbs and vegetables: parsley, kale, spinach, red cabbage, onions and broccoli
• Fruit: apples, cherries, grapes and pears

You do not need to eat every food on this list. Variety matters more than perfection.

Practical ways to support mental clarity

When your brain feels foggy, start with the foundations:

• Protect a consistent sleep routine.
• Eat regular meals with protein, fibre and colourful plant foods.
• Drink enough water across the day.
• Take short breaks from screens and mentally demanding work.
• Move your body daily, even if it is only a walk outside.
• Reduce multitasking and focus on one task at a time.
• Notice whether caffeine, alcohol or late-night scrolling are affecting your sleep.
• Speak with a health professional if symptoms are persistent, severe or accompanied by other changes.

Where Brain Health fits

For people looking for additional nutritional support, Brain Health was developed by Natural Medicine Neuroscientist Megan Wilks and has been trusted by practitioners since 2015.

Its botanical formulation includes selected flavonoid-rich extracts from German chamomile, citrus and cacao. It is designed to support cognitive function, mental clarity, healthy mood balance and everyday brain resilience.

Brain Health is intended to complement a healthy diet and lifestyle. It is not intended to diagnose, treat or prevent brain fog, chronic fatigue, hormonal conditions, nutrient deficiencies, depression, anxiety or other medical conditions.

Clearer thinking starts with curiosity

Brain fog is often a signal worth listening to.

Sometimes the answer is more sleep, better recovery, regular meals or less pressure. Sometimes it is a conversation with your GP. Often, it is a combination of small changes that help you feel more like yourself again.

Your brain does not need perfection. It needs consistent support.

Written by Megan Wilks Neuroscientist & Co-Founder.

👉 Learn more about Brain Health.