- Brain fog makes you feel like you can't think straight, focus, or stay completely alert.
- Sleep deprivation can cause fogginess because it makes your brain go into sleep-like rhythms.
- Brain fog can also be caused by hormonal changes, stress, certain medications, or infections.
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If you find yourself having trouble concentrating or feeling like you can't think straight, you may be experiencing brain fog. Brain fog isn't a diagnosis in and of itself, but it is a symptom that may occur alongside various medical conditions or certain life circumstances.
"When patients talk about experiencing brain fog, they usually mean difficulty with concentration and focus, sometimes with accompanying fatigue or a feeling of not being fully alert or aware," says Carolyn Fredericks, MD, neurologist at Yale Medicine and assistant professor of neurology at Yale School of Medicine.
It's important to discover the cause of your brain fog to determine how to treat it. Here are seven possible causes of brain fog.
1. Sleep deprivation
If you're temporarily sleep deprived, or sleep deprived due to a chronic condition such as insomnia or sleep apnea, this can result in brain fog.
"It seems like sleep deprivation can result in parts of the brain going into sleep-like rhythms during wakefulness," says Fredericks.
Additionally, she says that when you're sleep deprived, parts of your brain may not function as smoothly or coordinate as well with other parts of the brain, causing fogginess.
2. Hormonal changes
When women experience drastic hormonal changes, this may contribute to brain fog. For example, Fredericks says that women experiencing falling levels of estrogen during menopause may be more likely to have brain fog.
A 2021 study of pre-menopausal, peri-menopausal, and post-menopausal women found that menopause is linked to changes in brain structure and connectivity, which may account for neurogloigcal symptoms.
Furthermore, Fredericks says other changes of hormone levels, such as during pregnancy, can cause brain fog.
While more definitive research is needed, it's believed that the big shifts of hormones like estrogen and progesterone can impact brain circuits and cause the symptom, Fredericks says.
3. Stress and anxiety
It's common for people who suffer from stress and anxiety to feel regularly distracted and unable to focus, often complaining that their brain is foggy, says Thomas C. Hammond, MD, neurologist at Baptist Health's Marcus Neuroscience Institute.
A 2019 study found that stress and anxiety may have a negative effect on memory, contributing to brain fog.
4. Medications
Taking certain neurological medications may cause brain fog, says Fredericks. She says some common classes of drugs that result in this side effect are:
- Anticholinergic medications
- Benzodiazepines
- Opiates
- Antipsychotics
Other medications can cause brain fog even if they don't directly impact the brain, because of their mechanisms.
"For example, sometimes the medications for hypertension are diuretics, lowering sodium and potassium levels. These electrolyte changes alter the way these patients think, with many complaining they don't think as well as they did prior to being put on these medications," says Hammond.
5. Infections
If your body is fighting off an infection, its inflammatory response may be to blame for brain fog.
Fredericks says when the body experiences inflammation, cells called inflammatory cytokines signal a "sickness response" to the brain which is thought to be adaptive in some cases, forcing you to slow down and rest and focus on recovery. However, in some cases, brain fog may persist even after an infection is fought off.
For example, a 2021 study of COVID-19 survivors found that there was a relatively high occurrence of brain fog in patients months after recovering from the virus.
6. Autoimmune conditions
Common autoimmune conditions such as multiple sclerosis (MS) and lupus can cause brain fog, says Fredericks. There is ongoing research to determine why exactly the immune responses result in brain fog.
In the case of lupus, fMRI studies of the brains of lupus patients show abnormalities in brain processing efficiency, leading to changes in thinking and memory. With MS, you may get brain lesions, and the more brain lesions you have, the greater the likelihood of brain fog, says Fredericks.
7. Neurodegenerative diseases
Brain fog can be an early sign of neurodegenerative diseases such as Alzheimer's or Parkinson's, says Hammond. Oftentimes, these patients will complain that their thinking isn't the way it used to be, and that their cognitive processing is declining, Hammond says.
This is due to the fact that these diseases result in nerve cells in the brain losing their function and dying, resulting in overall cognitive decline.
Insider's takeaway
If you're experiencing brain fog, especially for a prolonged period of time, talk to your doctor.
Together, you can discuss any other symptoms you may be experiencing and determine what the underlying cause of your brain fog is.
From there, you can decide the best course of action to get you feeling better and thinking more clearly again.