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Brain Fog

Reviewed by Psychology Today Staff

Brain fog is a type of cognitive dysfunction characterized by poor memory, difficulty focusing, confusion, and mental fatigue. People who experience brain fog often describe their thinking as sluggish or “fuzzy” and report that they find it challenging to form coherent thoughts or translate those thoughts into words. For this reason, persistent brain fog can be a significant obstacle to academic and workplace success, as well as interfering with other aspects of day-to-day functioning.

Brain fog is not a formal diagnosis nor itself a medical condition; instead, it may be a symptom of one, such as depression, fibromyalgia, or COVID-19. Certain medications, chemotherapy, or pregnancy can also trigger brain fog. It may also be due to lifestyle factors, most notably poor sleep or heightened stress; indeed, most people can relate to feeling mentally “fuzzy” after a restless night or during a chaotic time at work. Identifying the cause of one’s brain fog is often the first step to managing it, either with medical interventions or, often, with lifestyle changes.

Symptoms and Causes of Brain Fog
Man sitting at his desk suffering from brain fog, rubbing his eyes

Different people experience brain fog in different ways, but in general, the symptoms of brain fog may include:

  • Forgetting appointments, tasks, or conversations
  • Difficulty recalling information or translating thoughts into words
  • Distractibility and difficulty concentrating
  • Slow or sluggish thoughts
  • Persistent mental exhaustion
  • A feeling of mental fuzziness or that one’s mind frequently goes blank
  • Feeling easily overwhelmed by routine or mundane tasks, or taking much longer to complete them than is normally required

The vast majority of people have experienced brain fog on occasion, as it can be brought on by quotidian factors like a night of poor sleep, jet lag, or even an overly heavy meal. It may also be caused by short-term physical and emotional stressors, such as being pregnant or navigating a difficult time at work or school. These cases of brain fog often resolve once the stressor has passed.

When brain fog is severe and persistent, however, it may indicate a more serious cause or one that requires formal treatment. Such causes can range from psychiatric conditions like anxiety, depression, or PTSD; to physical health conditions like vitamin deficiencies, COVID-19, multiple sclerosis, or cancer. Certain medical treatments, such as benzodiazepines or chemotherapy, may also induce brain fog; indeed, the term “chemo brain” refers to the brain fog that often occurs when undergoing cancer treatment.

Can stress cause brain fog?

Stress is a common cause of brain fog because stress—and especially chronic stress—keeps our nervous system on high alert. When our bodies and brains are operating in survival mode, we may not have the capacity to focus on minor tasks or engage in logical, rational thinking, resulting in persistent fuzziness or frequent feelings of overwhelm. 

Can medications cause brain fog?

Yes, certain medications, including some commonly prescribed ones, may include brain fog as a potential side effect. Some possible culprits include benzodiazepines, antihistamines, antiseizure medications, certain antidepressants, painkillers, and sleep aids. If you are worried that a medication is interfering with your cognitive function, talk to your doctor.

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Brain Fog and COVID-19
Woman with long COVID blowing her nose

Brain fog has become more well-known in recent years due in part to its connection with coronavirus disease 2019, or COVID-19. COVID is a highly infectious respiratory disease whose symptoms typically include coughing, difficulty breathing, fever, and headache. However, some people who contract COVID-19—and especially when their infection progresses to what’s known as long COVID, a protracted bout of the illness or a relapse after an apparent recovery—report symptoms of brain fog that often persist long after other symptoms such as fever have subsided.

The exact cause of COVID-induced brain fog is not yet entirely understood; indeed, there is much we still don’t know about the specific coronavirus that causes COVID-19 and how it behaves in the human body. Still, researchers have proposed several possible mechanisms to explain why COVID-19 and long COVID often trigger brain fog; these include neuroinflammation, damage to blood vessels impairing oxygen flow to the brain, and other hypotheses.

Is brain fog always a symptom of COVID-19?

Brain fog is a commonly reported symptom of both “regular” COVID and long COVID; in fact, patient surveys find that it is often among the earliest long COVID symptoms to appear. However, not everyone with COVID develops brain fog, and brain fog may itself be a symptom of countless other health concerns, from cancer to PTSD. 

How does COVID-19 lead to brain fog?

There are several possible reasons why COVID-19 can cause brain fog. Chief among them are infection of the central nervous system, neuroinflammation caused by the initial respiratory inflammation, an overactive autoimmune response, or damage to blood cells resulting in reduced oxygen to the brain. More research is needed to determine which of these causes are most likely.

How to Beat Brain Fog
Man standing outdoors, smiling up toward the sky because he beat brain fog

How brain fog is treated typically depends on its cause. Sometimes, treatment is as simple as replacing one medication with another; more often, however, managing brain fog requires some longer-term lifestyle changes, like improving one’s sleep quality, getting more exercise, or committing to a healthy diet. In certain cases, formal medical treatment may be appropriate; for example, brain fog thought to be caused by inflammation may be treated with immunosuppressant drugs or anti-inflammatories. Anyone struggling with persistent brain fog should reach out to a doctor to help identify the cause and determine the treatments that may help.

Can exercise help with brain fog?

Exercise is among the most commonly recommended treatments for brain fog, as physical activity benefits both the body and the mind. Those whose brain fog is caused by an illness, such as COVID-19, may find it especially difficult to engage in physical activity; starting small, and aiming for consistency rather than intensity, can help make an exercise habit easier to adopt.

Will getting more sleep cure my brain fog?

In many cases, yes, as an insufficient amount of sleep is a common factor in persistent brain fog. Aim for 7-9 hours of sleep a night and practice consistent sleep hygiene (i.e. going to bed and waking up at the same time each day, avoiding electronics before bed, and eliminating light from your bedroom); if brain fog continues even after several months of better sleep, reach out to a doctor for further help.

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