Written by Dr. Valentina Quintana MD on
August 8, 2022
Reading Time: 12 minutes

Medically Reviewed by our Medical Affairs Team

Written by Dr. Valentina Quintana MD on:

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Brain fog is a condition that plagues many people. It can be difficult to diagnose and even harder to treat. This is because brain fog has many different causes.

In this article, we will explore the research on brain fog and discuss the various causes of this often debilitating condition. We hope that this information will help you better understand brain fog causes and how to deal with it.

Let’s get started.

What is brain fog, exactly?

Brain fog or mental fog is a term used to describe a condition that causes mental fatigue, forgetfulness, and difficulty concentrating. This cognitive impairment can make it hard for you to think clearly or remember simple things.

Other common symptoms of brain fog include:

  • Difficulty focusing or paying attention
  • Being easily distracted
  • Mental fatigue
  • Physical fatigue
  • Problems with thinking clearly
  • Poor recall
  • Slow reaction time or processing speed
  • Low mood and irritability
  • Sudden mood swings
  • Taking more time to finish easy tasks
  • Difficulties with finding the right words in conversations
  • Trouble with organizing thoughts and activities

Take note that mental fog, in itself, is not a diagnosable condition but a symptom of an underlying cause.

It usually lasts for a few days to a few weeks. However, other people may experience this cognitive dysfunction for several months—depending on the severity of the cause or underlying condition.

Common Brain Fog Causes

Mental fuzziness can be caused by many different things. Below we will discuss some of the most common causes of mental fog according to research.


Chronic stress is what causes cognitive fog—at least it comes top of the list.

This is because when you’re stressed, your body releases cortisol—a hormone that helps you deal with stressful situations. While this hormone is essential for survival, too much of it can lead to problems like mental fog.

Cortisol affects the brain in multiple ways. It can interfere with brain function and impair your ability to think clearly. It can also disrupt your sleep, which further contributes to mental fog.

In one study, researchers found that chronic stress leads to changes in the brain that can cause problems that affect memory and learning.

The study participants who reported higher levels of stress had more difficulty recalling information than those who reported lower levels of stress.

Stress can also cause inflammation, which has been linked to mental fog and other cognitive problems.

If you’re struggling with chronic stress, there are many things you can do to manage it. Here are a few ideas:

  • Get regular exercise
  • Practice relaxation techniques like yoga or meditation
  • Connect with friends and family
  • Spend time in nature
  • Get some sunlight
  • Seek professional help

You can also try brain-boosting supplements like omega-three fatty acids, which have anti-inflammatory effects.

Exercise is also a great way to reduce stress and improve brain power. In one study, people who exercised regularly had better brain function than those who didn’t.

So, if you’re looking for ways to improve your brain fog, managing stress should be at the top of your list.

Lack of Sleep

Sleep is essential for brain health. It gives your brain a chance to rest and repair itself.

During sleep, your brain clears out toxins that can build up during the day and contribute to mental fog. Not getting enough sleep can disrupt this process and lead to problems with mental function and body function.

In one study, people who slept less than six hours a night had more difficulty concentrating and remembering information than those who slept seven to eight hours per night.

Sleep deprivation can also cause inflammation, which has been linked to brain fog and other cognitive disorders.

If you’re struggling to get adequate sleep, there are a few things you can do to improve your sleep habits.

  • Try to go to bed and wake up at the same time each day.
  • Create a relaxing bedtime routine.
  • Avoid caffeine and alcohol before bed.
  • Limit your exposure to blue light in the evening.
  • Make sure your bedroom is dark, quiet, and cool in temperature.

If you’re still having trouble sleeping, talk to your doctor—you might be dealing with a sleep disorder that requires a specialist.

Some of the common sleeping disorders that cause mental fog include:

  • Insomnia
  • Sleep apnea
  • Restless legs syndrome
  • Narcolepsy
  • Night terrors

Getting sufficient sleep is essential for mental clarity, so it’s important to make it a priority if you’re struggling with brain fog.

Poor Diet

What you eat has a direct impact on your cerebral function. Eating a healthy diet is essential for cognitive health, while an unhealthy diet can lead to problems like mental fog.

Studies show that there are a few different ways that diet can impact mental function.

First, certain nutrients are essential for cerebrum health. If you’re not getting enough of these nutrients, it can lead to problems with brain function.

Some of the most important nutrients for cognitive health include:

  • Omega-three fatty acids
  • Vitamin B12
  • Folate
  • Iron
  • Magnesium
  • Zinc

You can get these nutrients from foods like fish, leafy greens, meat, and poultry.

Second, a poor diet can cause inflammation, which has been linked to cognitive issues like brain fog.

Inflammation is a natural process that helps your body heal. But when it’s constantly activated, it can lead to problems like mental fog and cognitive decline.

There are many things you can do to reduce inflammation.

Here are a few of the best anti-inflammatory foods:

  • Turmeric
  • Ginger
  • Olive oil
  • Green tea
  • Berries
  • Nuts and seeds
  • Dark chocolate
  • Fatty fish like salmon

If you’re struggling with brain fog, make sure you’re eating a healthy diet that includes plenty of anti-inflammatory foods.

Other factors that constitute a poor diet are:

  • High sugar intake
  • Processed foods
  • Artificial additives
  • Too much caffeine and alcohol
  • Food allergy or sensitivities

To improve mental fog, cut out processed foods and unhealthy substances like artificial sugar, additives, and processed foods. Instead, focus on eating whole, nutrient-rich foods.

Nutritional Deficiency

A nutritional deficiency can lead to brain fog and other cognitive problems. This is because certain nutrients are essential for cerebral function, as we mentioned when it comes to your diet.

Some of the most common nutritional deficiencies that cause mental fog include:

Vitamin A deficiency

Research shows that vitamin A is vital to learning, behavior, and overall mental function. A deficiency in this nutrient can lead to problems like brain fog and cognitive decline.

You can get vitamin A from foods like carrots, sweet potatoes, squash, dark leafy greens, and eggs.

Vitamin B12 deficiency

Vitamin B12 is essential for healthy cognitive function. It helps with the production of red blood cells and the formation of myelin, which is a substance that protects nerve cells.

Studies show that vitamin B12 deficiency can lead to memory lapses, impaired cognition, and a sensation of numbness and tingling in the nerves, which is the common outcome of poor myelination.

You can get vitamin B12 from foods like meat, poultry, seafood, eggs, and dairy products.

Vitamin C deficiency

Vitamin C is an important nutrient for cerebrum health. It helps protect brain cells from damage and supports brain functions by helping brain cells properly use essential neurological chemicals, such as serotonin and dopamine.

Research shows that a vitamin C deficiency could lead to impaired cerebral function, oxidative stress, and an increase in amyloid accumulation and deposition, which is common in all patients with Alzheimer’s disease.

You can get vitamin C from foods like oranges, strawberries, broccoli, Brussels sprouts, and kale.

Vitamin D deficiency

Vitamin D is an essential nutrient for cognitive health. It helps with calcium absorption, which is essential for proper mental function.

Studies also show that people who are vitamin D deficient are more likely at risk for cognitive decline and dementia.

One study found that people with a vitamin D deficiency were more likely to experience a decline in brain function over a six-year period.

You can get vitamin D from sunlight, food such as fatty fish and fortified dairy products, and supplements.

Vitamin E deficiency

Vitamin E is a crucial nutrient for cognitive health. It’s a powerful antioxidant that helps protect brain cells from damage.

Research suggests that vitamin E is critical in preventing the loss of a very important molecule in the brain—docosahexaenoic acid (DHA).

DHA is an omega-three fatty acid that’s essential for cerebral function. It makes up a large part of the brain and is involved in cognitive function, brain development, and neurological health.

This is why a vitamin E deficiency has been linked to memory problems, issues with learning and mental function.

You can get vitamin E from foods like sunflower seeds, almonds, spinach, and avocados.

Iron deficiency

Iron is a vital nutrient for cognitive health. It’s necessary for the proper function of enzymes that are involved in brain functions and development.

Studies suggest that a lack of iron can lead to problems with learning, memory, and behavior. It can also cause fatigue, which can make it difficult to focus and pay attention.

You can get iron from foods like red meat, poultry, seafood, beans, and leafy green vegetables.

Magnesium deficiency

Magnesium is essential for sending messages between your brain and body. It works as the keystone for the NMDA receptors, which are located on nerve cells and help in brain development, memory, and learning.

Studies suggest that magnesium deficiency can lead to digestive system issues and neurological disorders from apathy to psychosis. While several studies reveal that Magnesium provides a neuroprotective action when transmitting nerve impulses between neurons.

You can get magnesium from foods like dark chocolate, nuts, seeds, and legumes.

Omega-3 deficiency

Omega-three fatty acids are essential for cerebral function as they promote cerebral blood flow. Brain imaging studies suggest that improved performance for a variety of cognitive tasks is associated with greater blood flow in specific areas of the brain.

Studies show that when you lack omega-3 fatty acids in your diet, the amount of DHA in your brain decreases, and this leads to deficits in memory and learning.

You can get omega-3s from fatty fish like salmon, mackerel, herring, and sardines. You can also get it from flaxseeds, chia seeds, and walnuts.

Zinc deficiency

Zinc is a mineral that’s essential for brain development and function. It plays a role in neurotransmission, which is the process of sending messages between neurons.

Studies suggest that zinc deficiency can lead to problems with learning and memory. It can also cause changes in behavior, such as irritability and aggression.

You can get zinc from foods like oysters, beef, chicken, legumes, and nuts.

Lack of exercise

Exercise is important for cerebrum health. It increases the levels of brain-derived neurotrophic factor (BDNF), which is a protein that helps with brain development, learning, and memory.

Studies show that exercise can help improve cognitive function in people of all ages. It can also help reduce the risk of developing Alzheimer’s disease and other dementias.

On the other hand, research reveals that the lack of regular exercise can lead to mental fog and poor cognitive performance.

So, if you want to keep your brain healthy and sharp, make sure to get regular exercise. Here are some tips to get started:

  • Choose an activity that you enjoy. This will make it more likely that you’ll stick with it.
  • Set realistic goals. If you’re just starting out, your goal might be to exercise three times a week for 30 minutes.
  • Find a workout buddy. Having someone to exercise with can make it more fun and motivating.
  • Get creative. Exercise doesn’t have to mean going to the gym. You can take a dance class, go for a walk in the park, or even do some yard work.

Medical Conditions

There are also several health conditions that often have brain fog as a symptom. If you’re experiencing a foggy head, it’s important to talk to your healthcare provider to rule out any underlying causes.

Here are some of the most common health conditions that can cause mental fog:


Anemia is a medical condition in which you don’t have enough healthy red blood cells to carry oxygen to your body’s tissues. This can lead to fatigue, shortness of breath, and brain fog.

Also, several current research lends credibility to the theory that anemia is a major risk factor for dementia.

If you think you are anemic, we recommend considering a blood test to verify your hemoglobin count.

Autoimmune diseases

Autoimmune diseases are conditions in which your immune system attacks your own body.

Many autoimmune disorders can cause mental fog, including lupus, celiac disease, and multiple sclerosis.

Research also shows that there is a link between autoimmune or inflammatory diseases and neuropsychiatric disorders, such as seizures, attention deficit disorders, and migraines, among many others.

Multiple Sclerosis

Multiple sclerosis (MS) is a chronic, degenerative disease of the central nervous system. It can cause a variety of symptoms, including brain fog.

Other symptoms of MS include fatigue, muscle weakness, difficulty walking, and problems with vision.

According to studies, over half of individuals living with MS will develop cognitive difficulties. People may experience such problems as forgetfulness, difficulty focusing, and confusion.

Thyroid disorders

Thyroid disorders are conditions that affect the thyroid gland, which is a small gland in the neck that produces hormones.

The two most common thyroid disorders are hypothyroidism and hyperthyroidism.

Hypothyroidism, or an underactive thyroid, is the most common type of thyroid disorder. It occurs when the thyroid gland doesn’t produce enough hormones.

Hyperthyroidism, or an overactive thyroid, occurs when the gland produces too much hormone.

Research shows that both of these conditions can cause mental fog, along with other symptoms like fatigue, weight gain or loss, and mood changes.

Chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is a condition characterized by extreme fatigue that doesn’t improve with rest.

Other symptoms of CFS include brain fog, sleep problems, muscle pain, and headaches.

Studies show that people with CFS often have difficulty with attention and concentration. They may also have problems with short-term memory.


Fibromyalgia is a condition that causes pain and tenderness in the muscles, joints, and tendons.

It can also cause mental fog, fatigue, sleep problems, and mood changes.

Research suggests that fibromyalgia may be caused by an imbalance of brain chemicals. This can lead to problems with memory and concentration.

Hormonal imbalance

Hormonal imbalances can occur at any time in life, but they’re most common during puberty, period, pregnancy, perimenopause, and menopause.

They can cause a variety of symptoms, including brain fog. Other symptoms of hormonal changes include fatigue, weight gain or loss, mood changes, body temperature issues, and sleep problems.

Studies show that hormones, or the lack thereof, can influence neuronal networks and mental function, so it is important to make sure that you have balanced hormones.


Diabetes is a condition in which the body doesn’t produce enough insulin or can’t use insulin effectively.

This can cause a variety of symptoms, including mental fog. Other symptoms of diabetes include fatigue, weight loss or gain, and increased thirst and hunger.

Research shows that diabetes can damage the blood vessels and nerves. This can lead to problems with memory, concentration, and decision-making.


Hypertension, or high blood pressure, is a condition in which the force of your blood against your artery walls is too high.

This can cause a variety of symptoms, including brain fog. Other symptoms of hypertension include fatigue, headaches, and nosebleeds.

Studies reveal that hypertension can damage the arteries and lead to problems with blood flow. This can cause problems with memory, thinking, concentration, and overall cognitive decline.


Migraine is a type of headache that can cause a variety of symptoms, including mental fog.

Other symptoms of migraine include nausea, vomiting, and sensitivity to light and sound.

Studies show that people with migraines often have problems with attention and concentration. They may also have difficulty with short-term memory and may experience overall cognitive impairment.


Cancer is a disease in which cells in the body grow out of control.

It can cause a variety of symptoms, including brain fog. Other symptoms of cancer include fatigue, weight loss or gain, and changes in appetite.

Studies show that cancer can damage the brain and lead to problems with memory, thinking, and concentration.

Cancer treatments, such as chemotherapy can also cause brain fog as a side effect, also known as “chemo brain.”


Covid-19 is a novel coronavirus that was first identified in 2019.

This virus can cause a variety of symptoms, including brain fog. Other symptoms of Covid-19 include fever, cough, and shortness of breath.

Studies show that Covid-19 can damage the lungs and lead to problems with breathing. This can cause inflammation in the brain and lead to other cognitive problems.

Mental Health Conditions

Other than medical conditions that primarily affect the physical health of an individual, there are several mental conditions that cause mental fog and impair brain function, such as the following:


Depression is a mental condition that causes feelings of sadness, hopelessness, and fatigue.

Other symptoms of depression include brain fog, rumination, sleep problems, and weight changes.

Studies show that people with depression often have poor concentration or short attention span. They may also have difficulty with short-term memory and overall cerebral function.


Anxiety is a mental condition that causes feelings of worry, unease, and stress.

Other symptoms of anxiety include headaches, mental fog, heart palpitations, and irritability.

Research suggests that people with anxiety often have problems with memory, concentration, and decision-making.


Post-Traumatic Stress Disorder (PTSD) is a mental condition that can occur after a person experiences or witnesses a traumatic event.

Symptoms of PTSD include flashbacks, nightmares, brain fog, and avoidance.

Studies show that people with PTSD often have problems with memory and concentration. They may also have difficulty with decision-making and overall mental function.


Attention Deficit Hyperactivity Disorder (ADHD) is a mental condition that causes problems with attention, hyperactivity, and impulsivity.

Other symptoms of ADHD include mental fog, restlessness, and difficulty completing tasks.

Research suggests that people with ADHD often have problems with short-term memory, concentration, stillness, and overall brain function.


Obsessive-Compulsive Disorder (OCD) is a psychiatric health condition that causes problems with obsessions and compulsions.

Other symptoms of OCD include brain fog, anxiety, and avoidance.

Studies show that people with OCD often have problems with attention, concentration, memory, and decision-making.

Bipolar Disorder

Bipolar Disorder is a mental condition that causes extreme mood swings.

Symptoms of bipolar disorder include mental fog, mania, and depression.

Research suggests that people with bipolar disorder may have memory, attention, decision-making, and cognitive performance issues in addition to those associated with the illness.

Neurological Disorders

Besides common mental conditions, there are also several neurological disorders that can cause brain fog and cognitive impairment, such as the following:


Schizophrenia is a brain disorder that causes problems with thinking, feeling, and behavior.

Symptoms of schizophrenia include mental fog, delusions, hallucinations, and disorganized speech.

Studies show that people with schizophrenia often have problems with attention, memory, and executive function.


Dementia is a brain disorder that causes problems with memory, thinking, and behavior.

Symptoms of dementia include brain fog, confusion, delusions, and hallucinations.

Research suggests that people with dementia often have problems with attention, short-term memory, language, visuospatial ability, and executive function.

Alzheimer’s Disease

Alzheimer’s disease is a type of dementia that affects the brain and its functions, such as memory and thinking.

Mental fog, confusion, delusions, and hallucinations are some of the symptoms of Alzheimer’s disease.

According to studies, people with Alzheimer’s disease frequently have deficits in attention, short-term memory, language, visual-spatial ability, and executive functioning.


Amyotrophic Lateral Sclerosis (ALS) is a neurological disorder that affects the brain and spinal cord.

Symptoms of ALS include brain fog, weakness, paralysis, and difficulty speaking.

Studies show that people with ALS often have problems with attention, short-term memory, and executive function.

Parkinson’s Disease

Parkinson’s disease is a brain disorder that affects movement.

Symptoms of Parkinson’s disease include mental fog, tremors, rigidity, and slowness.

Research suggests that people with Parkinson’s disease often have problems with attention, short-term memory, language, and executive function.

Concluding Thoughts

Dealing with brain fog is never an easy feat—it can be frustrating and debilitating, affecting your day-to-day life.

Most people who have mental fog often experience a loss of productivity at work or school and an overall decreasing enthusiasm for life.

Thankfully, there are several things that you can do to help improve cerebral function and cognitive performance, such as getting regular exercise, eating a healthy diet, playing brain games, and getting enough sleep.

And if you believe that you or someone you know is experiencing brain fog, it is best to consult with a health professional to rule out any underlying conditions.

If you want to learn more about brain health and brain fog treatment, make sure to check out the rest of the articles on our website and join our online community.

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