Make sure you eat and take some supplements. Drink a lot of water, get some fresh air. Sometimes a good strong cup of coffee! These things seem to help me a little bit when I feel like that. But I really dont know what will make it clear up completely. Wish I knew. I tend to think it is part of my illness. Who knows, maybe its the meds I am taking. I struggle with brain fog a lot. BP really has taken a toll on me in terms of my endurance.