10 Possible Causes of Brain Fog

You may have experienced "brain fog," or the sluggish, cloudy feeling you get in your head when you can't focus. Symptoms can include feeling exhausted but not being able to sleep, forgetting things, or making simple mistakes.

These cognitive difficulties have been linked to long COVID, which can occur after COVID-19 infection. The link isn't exactly clear, but some evidence suggests that inflammation can trigger brain fog. Several other health conditions—such as depression and lupus—can also cause brain fog.

Brain fog exists on a spectrum. It's a frustrating—even debilitating—daily part of some people's lives. Making changes to your diet, exercise, and sleep habits are some ways for how to get rid of brain fog.

What Is Brain Fog? 

"Brain fog" is a colloquial term that describes cognitive difficulties. Physician Georg Greiner was one of the first to use "brain fog" in the 1800s to describe delirium. This mental state causes an inability to think clearly. People have used "brain fog" to explain mental lethargy that often accompanies several health conditions. 

Research has found that inflammation in the brain triggers brain fog. The nerve cells in different regions of the brain send signals to each other to communicate and help you focus, perform tasks, and think clearly. Inflammation in the brain damages these nerve cells, making it hard for them to transmit signals.

Symptoms

Brain fog symptoms may include:

• Feeling mentally "fuzzy"
• Inability to think clearly
• Lack of mental clarity
• Memory problems
• Spacing out
• Trouble concentrating

What Causes Brain Fog?

Brain fog has been linked to long COVID, which is a group of symptoms that can persist for weeks, months, or years after COVID infection. Some people have reported extreme fatigue, memory problems, and trouble concentrating after having COVID.

The link between brain fog and COVID is not extremely clear. This symptom can also occur with other conditions, including depression and lupus. You may experience brain fog if you have a lack of sleep, hormone changes, or stress.

1. COVID-19

Brain fog is a commonly reported symptom of long COVID. Some evidence suggests that nearly one-third of people have cognitive difficulties for weeks or months after COVID infection.

Anyone can develop long COVID, but risk generally increases with the severity of COVID symptoms. Vaccination helps decrease your risk of severe illness and, possibly, long COVID. Antiviral medicines, like Paxlovid (nirmatrelvir/ritonavir), help reduce the severity of illness if you get sick.

2. Chronic Fatigue Syndrome (CFS)

Chronic fatigue syndrome (CFS) causes cognitive and physical fatigue that lasts more than six months. CFS is also known as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Rest often doesn't improve symptoms.

Experts don't know the cause of CFS. Some evidence suggests that widespread inflammation in the brain may be the culprit. People with CFS often have brain fog symptoms like difficulty concentrating and sluggish thinking.

There's no cure for CFS, but a healthcare provider can advise treatments to manage symptoms. Antidepressants and therapy can alleviate CFS symptoms. Other treatments like massage, meditation, and yoga may also help improve brain fog.

3. Depression

Depression often causes a loss of interest in your favorite activities and persistent sadness. You may find your thinking and speaking slow, or you need help focusing, making decisions, and remembering things.

Other depression symptoms can include changes in appetite, feeling helpless or hopeless, and trouble sleeping. A healthcare provider can prescribe treatments to help manage these symptoms. Treatments include antidepressants, talk therapy, or a combination of both.

4. Hormone Changes

Changes in hormones, such as during periods, pregnancy, and menopause, may cause cognitive difficulties. Brain fog, also known as "period brain," may be a premenstrual syndrome (PMS) symptom.

Changing amounts of estrogen and progesterone throughout the menstrual cycle may affect cognitive function. Research has found that some people have difficulty concentrating after ovulation and before their period begins.

You may have heard the term "pregnancy brain" when referring to the brain fog that some pregnant people have. A study published in 2014 found that pregnant and postpartum people commonly self-report memory difficulties.

Menopause occurs 12 months after your last period, typically during your 40s or 50s. Research has found that menopausal people often report feeling forgetful and having difficulty concentrating.

5. Lack of Sleep

You may have frequent, severe brain fog if you have a sleep disorder that causes a lack of sleep. Some of the most common sleep disorders include:

• Insomnia: An inability to fall or stay asleep or both
• Narcolepsy: Excessive daytime sleepiness
• Restless legs syndrome: A "creeping" sensation that causes leg pain, particularly at night
• Sleep apnea: "Gasping," snoring, or stopping and beginning breathing while you sleep

These sleep disorders may lead to tiredness. A lack of sleep can cause brain fog-related symptoms like difficulty completing tasks, feeling confused, and problems with paying attention.

Treatment depends on the sleep disorder but typically involves practicing good sleep habits. Try waking up and going to bed at the same time every day. Avoid looking at your phone before going to sleep, and make sure your bedroom is cool, dark, and quiet.

6. Lupus

Lupus is a chronic autoimmune disorder, meaning the immune system mistakes healthy cells as invaders and attacks them. It causes inflammation and pain. Systemic lupus erythematosus (SLE), one of the most common forms of lupus, affects 200,000 adults in the United States.

Lupus may cause brain fog, also known as "lupus fog," which may lead to symptoms like:

• Confusion
• Difficulty concentrating
• Difficulty keeping a schedule or remembering names
• Lapses in memory
• Problems with processing thoughts
• Trouble completing familiar tasks

Lupus-related brain fog usually ebbs and flows. Brain fog may interfere significantly with daily life in some people. 

Talk to a healthcare provider about treatments that may address your symptoms and ways to avoid memory issues. You can do puzzles, read books, or use planners or color-coded calendars.

7. Multiple Sclerosis (MS)

Multiple sclerosis (MS) is a chronic inflammatory disease that causes lesions on the central nervous system. These lesions often affect cognition, emotions, how you think, and motor function.

MS brain fog "commonly affects the speed at which people can process information and their ability to recall things," Kathleen Costello, RDN, associate vice president of healthcare access of the National MS Society, told Health. Brain fog may also cause you to have difficulty making decisions or remembering how to do a job.

Some evidence suggests an overlap of MS with sleep disorders. Having no or restless sleep can exasperate brain fog.

Talk to a healthcare provider about MS treatments that help alleviate brain fog. They may advise some workaround strategies. Consider creating quiet environments for working, making checklists, and using memory aids.

8. Stress

Anxiety is a response to stress that causes feelings of fear. Research has found that anxiety and stress may cause brain fog-related symptoms like impaired memory.

The aftermath of stress-related brain fog could lead to worse feelings about yourself and make it difficult to reach out for help. Treatment options are available. Many effective medicines and forms of therapy that treat mood disorders might manage cognitive symptoms.

9. Cancer

Brain fog is a common side effect of chemotherapy. People often refer to cognitive difficulties during cancer treatment as "chemo brain." People with chemo brain may notice difficulty finding the right words, spacing out, or trouble recalling memories.

A healthcare provider may advise cognitive rehabilitation, exercise, and meditation to manage chemo brain. Cognitive rehabilitation involves activities like doing word puzzles or using a planner to improve brain function.

10. Other Health Conditions

Brain fog has been linked to several other health conditions that cause fatigue and inflammation. You may notice brain fog if you have:

• Attention deficit hyperactivity disorder (ADHD)
• Allergies
• Celiac disease
• Fibromyalgia
• Kidney failure
• Lyme disease
• Migraine
• Sjögren's syndrome
• Thyroid disease

Diagnosis 

Brain fog is a symptom of several health conditions, so no guidelines exist for diagnosing it. A healthcare provider may conduct a differential diagnosis to narrow down what's causing your brain fog.

Differential diagnosis is a process of ruling out health conditions that resemble your symptoms. A healthcare provider will likely order lab tests based on your health history, physical exam, and symptoms. They may conduct a mental health screening to check for mood disorders like anxiety and depression.

How To Get Rid of Brain Fog

Some evidence suggests that treating the underlying cause of brain fog helps alleviate cognitive difficulties in three months. Cognitive behavioral therapy (CBT) is a type of therapy that helps you cope with anxiety and depression, which may be a cause of brain fog.

Occupational therapy is another option to help people with cognitive, physical, or sensory barriers. It may help you cope with MS, for example, which can cause brain fog.

Lifestyle Changes

The following lifestyle changes may help you deal with brain fog:

• Diet: An anti-inflammatory diet may reduce inflammation in the brain. The Mediterranean diet, for example, can help with brain fog. It includes primarily plant-based foods, lean meat, and whole grains, limiting red meat and sweets. The Mediterranean diet may decrease inflammation and provide the body with essential nutrients.
• Exercise: Regular physical activity supports mental functioning. Exercise supplies oxygen to the brain, which strengthens communication between nerve cells. Experts advise 150 minutes of exercise per week. That's 30 minutes per day, five days per week.
• Sleep: A lack of sleep may cause or worsen brain fog. Adults need seven to eight hours of sleep nightly to support mental and physical functioning.

When To Contact a Healthcare Provider

Many people have brief instances of brain fog or moments when they have trouble finding the right words, focusing, and remembering things. These moments usually don't last very long. You may consult a healthcare provider if cognitive difficulties persist for several weeks or longer and impact daily activities.

Brain fog may be a sign or symptom of several health conditions. Keep track of your symptoms, including when they started, to share with a healthcare provider. Note what triggers your brain fog and what helps resolve it.

A Quick Review

Brain fog can come with overexertion, poor sleep, and stress. Persistent brain fog may be a sign or symptom of a health condition, like CFS, depression, or long COVID.

Consult a healthcare provider if you develop brain fog that doesn't go away and interferes with daily activities. A healthy diet, exercise, and sleep typically help alleviate brain fog. Other treatments may include CBT or occupational therapy, in which you learn ways to manage cognitive difficulties.