We’ve all been there—staring blankly at a computer screen, forgetting a name mid-sentence, or losing track of what we were about to do. This mental haziness, commonly referred to as brain fog, is more than just an occasional lapse in concentration. While often benign and temporary, persistent brain fog can signal deeper health issues that shouldn’t be ignored.
So, what exactly causes brain fog, and how can you tell when it’s time to seek medical advice? In an exclusive interaction with the editorial team of Onlymyhealth, Dr Shrey Kumar Srivastav, Senior Consultant and General Physician, Sharda Hospital - Noida, explained everything you need to know!
What Is Brain Fog?
Brain fog isn’t a medical diagnosis but rather a term used to describe a constellation of cognitive symptoms: confusion, forgetfulness, lack of focus, and mental fatigue. It can feel like your brain is operating in slow motion, and tasks that once felt routine may suddenly become overwhelming.
Common Causes of Brain Fog
According to Dr Srivastav, a few causes of brain fog may include:
Lack of Sleep
Inadequate or poor-quality sleep disrupts cognitive processes like memory consolidation and attention. Even a few nights of restless sleep can lead to foggy thinking.
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Stress and Anxiety
Chronic stress floods the brain with cortisol, impairing memory and concentration. Over time, this can lead to fatigue and burnout—both of which contribute to brain fog.
Poor Diet
Diets high in sugar, processed foods, or low in essential nutrients (like B vitamins, omega-3s, and antioxidants) can affect brain health. Dehydration and low blood sugar levels can also impair cognition.
Hormonal Changes
Hormonal shifts during pregnancy, perimenopause, or thyroid imbalances (such as hypothyroidism) are known culprits. Estrogen, progesterone, and thyroid hormones all influence brain function.
Medication Side Effects
Some medications, including antihistamines, sedatives, and antidepressants, list brain fog as a side effect. If brain fog began after starting a new medication, this could be the cause.
Medical Conditions
Conditions such as fibromyalgia, chronic fatigue syndrome, multiple sclerosis, and autoimmune diseases like lupus can lead to persistent mental cloudiness.
Mental Health Disorders
Depression and anxiety don’t only affect mood, but they also can cloud thinking and reduce mental clarity, thereby leading to a brain fog.
When Is Brain Fog a Concern?
Dr Srivastav highlighted that while occasional brain fog is usually nothing to worry about, there are red flags that may indicate an underlying health issue. Here is the list of symptoms he shared with us:
Persistent symptoms lasting more than a few weeks
Worsening memory or difficulty with everyday tasks
Accompanied symptoms like fatigue, dizziness, mood changes, or unexplained weight changes
Interference with work or daily life
Sudden onset, especially if accompanied by slurred speech, numbness, or vision problems (seek immediate medical help—these could be signs of a stroke or neurological issue)
How to Clear the Fog: Lifestyle Tips
If your brain fog isn’t linked to a serious health issue, lifestyle adjustments can make a big difference:
Prioritise sleep: Aim for 7–9 hours of quality rest per night.
Eat for your brain: Include omega-3-rich foods, leafy greens, lean proteins, and plenty of water.
Manage stress: Practice mindfulness, exercise, or seek therapy if needed.
Exercise regularly: Physical activity boosts blood flow and promotes mental sharpness.
Take breaks: Avoid multitasking and give your brain a rest throughout the day.
Bottomline
Brain fog is your brain’s way of telling you something’s off. While it’s often related to stress, lifestyle, or minor health issues, persistent or severe symptoms shouldn’t be brushed off. If your mental cloudiness feels like more than just a rough day, talk to a healthcare provider.
Your brain does a lot for you—taking care of it is one of the most important investments in your long-term wellness.
[Disclaimer: If you're experiencing ongoing brain fog, consider keeping a symptom journal to share with your doctor. The more insight you have into when and how it occurs, the easier it is to pinpoint the cause.]