I feel a lot of anxiety and fogginess in the daytime, almost like a drunk person. but at night i'm clear headed and very relaxed and i feel that my brain starts to work again. what's the reason for this?

Some people are 'night' people and some are 'day' and some can adjust to both. it depends on one's inherent diurnal function controlled by some centers in the brain. How and why is not known. But most people can modify this. But ii your symptoms persist a neurologic evaluation might be need. In th mean time get good sleep, eat healthy and stay away from strong stimulants. Good luck