“Brain fog” isn’t a formal medical diagnosis but rather a descriptive term for the feeling of cognitive fuzziness - difficulty concentrating, lapses in memory, or just mental sluggishness. According to a recent NDTV overview, a variety of factors can trigger it. 

One of the most common is lack of sleep: without the recommended 7-9 hours of good rest, the brain’s ability to focus and process information drops sharply. Chronic stress and anxiety also elevate cortisol, which can interfere with memory and attention. 

What you eat matters too. Poor nutrition - such as excessive sugar, processed foods, or dehydration - robs the brain of energy and vital nutrients. Hormonal shifts - like those from hypothyroidism or menopause - can slow cognition, while medical conditions like autoimmune disorders or chronic fatigue syndrome often bring brain fog along with them. 

Sometimes, medications (antihistamines, antidepressants, sleep aids) list brain fog among side effects, or ongoing infections and inflammation disrupt neural signaling. 

If brain fog is interfering with daily life, it’s often a sign to review sleep habits, diet, stress levels—and consult a healthcare provider to rule out underlying issues.