If you are more disciplined than me, meditation in place of napping could work. But napping is easier and more enjoyable to me.
As for brain fog itself, I think proper nutrition is very important. Our body needs many different micronutrients to operate at optimal capacity and many peoples' diets don't meet these.
Lastly, I don't know how true this is, but a chiropractor told me that poor neck posture can result in reduced blood flow to the brain which can reduce your cognitive capacity (i.e. feeling of brain fog).