What Is Brain Fog and How to Beat It

December 8, 2023
man with brain fog

Brain fog is not a diagnosable medical condition. Instead, it is a constellation of symptoms affecting thinking and memory. Many people have experienced temporary brain fog. We all have those days when we lose track of what we are doing, can’t remember where we put our keys and phone, repeat ourselves when giving instructions, or miss an appointment on our calendar. If you are experiencing brain fog, you may notice you are constantly jotting notes on your phone, a major change from when you could juggle multiple things simultaneously. 

Cognition is the ability to use knowledge. Most people don’t think about how well their brain works until they have problems. If your brain fog is persistent or associated with any other symptoms, schedule a consultation with your healthcare provider. While stress and lack of sleep are common contributors to the symptoms associated with brain fog, it is important to determine whether you have a medical condition or a nutrient deficiency causing your symptoms. 

What Is Brain Fog?

Brain fog is that mentally fuzzy feeling that makes it difficult to focus and recall essential information. Many describe it as mental fatigue.1 

Some of the common symptoms that characterize brain fog include2,3 

  • Difficulty concentrating
  • Memory lapses
  • Difficulty processing information
  • Fatigue
  • Trouble paying attention
  • Taking longer to solve a problem or make a decision
  • Difficulty multitasking
  • Slow thinking
  • Difficulty focusing
  • Confusion

Brain fog causes stress. It may even cause anxiety or depression, which can worsen brain fog symptoms. When your thinking is cloudy, it is likely to affect your physical performance.  This can add to your stress and aggravate your symptoms.

Graphic of health metrics

What Causes Brain Fog?

Since brain fog is a collection of symptoms rather than a medical disease, it does not have characteristic signs and symptoms that can be used to diagnose it, physical findings that support a physiological abnormality, or labs and tests that can be used to support the diagnosis. With that said, the collection of symptoms that characterize brain fog is fairly well defined and consistent across many medical conditions. 

The lack of diagnostic qualities for brain fog makes it difficult to determine causes and risk factors. However, most people with the following conditions can relate to the feeling of brain fog. Something has changed in the brain. It is not working at its usual level of efficiency and capacity. Whether it’s lack of sleep, stress, infection, nutritional deficiencies, or hormone imbalances, something is using more cognitive resources, making your brain less efficient. 

Lack Of Sleep

Do you get the recommended 7 to 9 hours of quality sleep each night? Sleep is an active process. Sleep gives your brain time to repair damaged cells, restore nutrients, and remove waste. Sleep deprivation causes changes in the brain that contribute to slow cognitive performance. As sleep debt builds up, communication between brain cells slows, negatively impacting attention and memory.4 

Lack of sleep increases inflammation, blood pressure, and cortisol secretion, which can worsen brain fog symptoms. Both total and chronic partial sleep deprivation can cause attention and working memory problems.5 


Chronic stress increases cortisol release, which causes physiological changes throughout your body, including increased heart rate and blood pressure, increased blood sugar, decreased immune function, disrupted sleep, gastrointestinal symptoms, and anxiety, depression, memory, and concentration problems.   

Chronic stress can cause structural changes in the brain that contribute to cognitive problems and symptoms associated with brain fog. Mild stress can cause an improvement in cognition, but over a certain threshold, it causes cognitive disorders, especially with memory and judgment.6 

A woman with an illness


COVID-19 is caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. It has become increasingly apparent that COVID-19 causes both short-term and long-term brain symptoms. 

Brain symptoms linked to COVID-19 include7

  • Headache
  • Confusion
  • Fatigue
  • Dizziness
  • Lack of smell
  • Lack of taste
  • Brain infections
  • Decreased consciousness

Researchers estimate that about 43% of people with COVID-19 experience long-term symptoms. This number increases to 54% for hospitalized patients.8 In one study, 7.2% of adults aged 18 to 55 reported symptoms consistent with brain fog after a COVID-19 illness.9 In another small study, 59% to 65% of patients with COVID-19 demonstrated cognitive impairment.10 The average recovery time was 14.8 months.11

Nutrient Deficiencies

Inflammation and oxidative stress damage cells. Inflammatory processes are likely the underlying cause of cognitive dysfunction and are strongly implicated in Alzheimer’s disease. Good nutrition supports the immune system and decreases inflammation. Eating foods high in antioxidants provides your brain and body cells with the nutrients they need to optimize cellular function.12 

Avoid processed foods, foods high in saturated fats, and simple sugars. The Mediterranean and dietary approaches to hypertension (DASH) diets may be neuroprotective because they reduce inflammation and protect cognitive function.12 


Estrogen, progesterone, and testosterone are intimately involved in brain function. These sex hormones decrease inflammation, increase blood flow to the brain, and increase connections between nerve cells.

Sex hormones also influence brain circuits that are involved in memory, attention, and other cognitive functions. Estrogen receptors are concentrated in the hippocampus and the prefrontal cortex. These two key brain regions are involved in learning, memory, and higher-order cognitive function.13,14 

Perimenopause is associated with fluctuating estrogen and progesterone, followed by menopause when these hormones precipitously drop. Decreasing estrogen levels are associated with a decline in cognitive function and an increased risk of depression and other cognitive symptoms in menopause.15

women holding her head

Hormonal Conditions

Besides changes in the sex hormones estrogen, progesterone, and testosterone, other hormone imbalances may contribute to brain fog. In a study of over 5,000 patients with thyroid disease, 47% reported symptoms consistent with brain fog before treatment, and 79% reported that they experienced the symptoms frequently. Many people with low thyroid function (hypothyroidism) report symptoms even after treatment.16  

How To Get Rid of Brain Fog

Brain fog is typically self-limiting, especially if it is caused by lifestyle factors such as stress and lack of sleep. However, if brain fog symptoms persist or worsen, call your healthcare provider. It is relatively rare that medical conditions cause brain fog, but as we have seen with COVID-19, it can happen. 

Sleep, Exercise, And Nutrition

Reducing stress, making exercise a daily part of your routine, and consuming a healthy diet all benefit overall health and brain health. Daily exercise can improve insulin sensitivity and reduce inflammation. Increase protein, decrease simple sugars, and increase healthy fats in your diet to Naturally Regulate Your Hormones

Prioritize these foods in your diet: 

  • Fruits 
  • Green, leafy vegetables
  • Berries
  • Fish
  • Flaxseed 
  • Nuts 
  • Oil
  • Fermented foods
  • Green tea
  • Beans

A healthy diet and exercise can have the following benefits: 

  • Reduce inflammation 
  • Support immune function
  • Improve cardiovascular function 
  • Maintain a healthy weight
  • Maintain bone density and muscle strength
  • Preserve brain function
  • Maintain a healthy libido

Learn more tips about How to Stay Healthy with Age

low carb mood changes

Vitamins For Brain Fog

Taking an inventory of your current lifestyle and making any necessary changes should be the first step in treating brain fog. Sometimes supplements are necessary, especially when your diet does not supply the nutrients your brain needs to function optimally. With aging, some vitamins and nutrient levels decline. If your levels of these key nutrients are low, consider supplements to support your cognitive health

  • Vitamin D: About 40% of U.S. adults are vitamin D deficient. Not having enough vitamin D can contribute to brain fog symptoms and negatively affect cognitive health. Vitamin D supplementation can improve mood and reduce anxiety and depression, which can also reduce brain fog symptoms. Learn more in this Ultimate Guide to Vitamin D
  • B-complex vitamins: B12 is essential for forming red blood cells. If you have anemia from a lack of iron or B12, your brain may not get optimal amounts of oxygen, making it feel tired and foggy. Read more about B12 supplementation in Vitamin B12 Supplementation, an Overview.  
  • Omega-3s: Omega-3 fatty acids may support brain and eye health. They are found in plants and oily fish. Several studies support the impact of omega-3 fatty acids on cognitive function.17 A systematic review of fourteen studies found that ten studies demonstrated that omega-3 fatty acids had a positive effect on cognition. Omega-3 fatty acids are a supplement that also improves other menopausal symptoms.   
  • Other immune-boosting vitamins like Vitamin C and E: Two important antioxidants, Vitamins C and E, can help support immune function by neutralizing free radicals and protecting your body and brain cells from oxidative stress. While your diet is the best source of these important nutrients, read can vitamin supplements improve overall brain health? to learn more about these vitamins. 
  • NAD+: Nicotinamide adenine dinucleotide (NAD+) is a coenzyme and signaling molecule. NAD+ declines with age. It is required to transfer energy from your diet to cells in your body, where the nutrients can be used for cellular growth and repair. NAD+ is a cofactor involved in hundreds of chemical reactions. Replenishing NAD+ levels can improve sleep and mental clarity.  
What Is Brain Fog and How to Beat It

Consult Your Physician

Brain fog is a constellation of symptoms that affect concentration and memory. It is commonly described as a type of mental fatigue. Lifestyle factors such as stress, lack of sleep, poor dietary choices, and hormonal changes can contribute to these symptoms. However, brain fog is not well understood, so if you are concerned about your symptoms, it is important to relay these concerns to your doctor to ensure you are properly evaluated for any potential underlying health conditions. The odds are good that your symptoms can be improved with lifestyle and dietary changes, but brain fog is also linked to serious medical conditions such as long-term COVID-19, chronic fatigue syndrome,3 and chronic anxiety or depression.18

Author: Leann Poston, M.D.
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