Brain fog is a type of cognitive dysfunction and is described as the inability to have sharp thoughts, memory or focus, as well as poor concentration and a lack of mental clarity. Unaddressed brain fog can interfere with everyday activities and quality of life. It can be caused by a range of lifestyle factors, medications with brain fog side effects, and certain conditions. A major cause of brain fog is inadequate sleep (due to a reduced number of sleeping hours) - this can affect concentration. Stress is another main factor - it can increase blood pressure, weaken the immune system, trigger depression and cause mental fatigue. A diet lacking Vitamin B-12 can cause brain fog - B12 is needed for the formation of red blood cells and the maintenance of the central nervous system; decreased vitamin D levels are also associated with impaired cognitive function. Certain food allergens such as MSG, aspartame, peanuts, and dairy, can also contribute to brain fog. Medical conditions associated with mental fatigue include chronic fatigue syndrome, anemia, depression, diabetes, Sjögren syndrome, migraines, Alzheimer’s disease, hypothyroidism, Fibromyalgia, autoimmune diseases such as lupus, arthritis, and multiple sclerosis. As brain fog is not a medical condition itself, there are no methods to diagnose it. Brain fog is a symptom of other medical conditions, suggesting an underlying issue. Generally, a doctor would conduct a physical examination, enquire about health history, carry out a blood test and an allergy test. X-rays, MRI, or CT scans may also be used during a diagnosis. Treatment for brain fog is cause-dependent, but commonly include iron supplements for anemic patients, corticosteroid for autoimmune diseases, sleeping 8 to 9 hours each night, limiting and avoiding excessive alcohol and caffeine, increasing physical activity, and eating a nutritionally balanced diet of protein, fruits, vegetables, and healthy fats. Psychological interventions include Cognitive behavioral therapy and Dialectical Behavior Therapy.