exam stress....!!!!

Exam is on tomolo... and i cant get a single bits of my notes into my head... and i m damn seriously hooked on nicotine n alcohol fixed due to all the stress... wishing that when i was in london, time could pass slower so i dun have to come back to face the exams... it's been a long long while since i last sat for an exam... why is everything so difficult to digest and just dont seem to get into my head despite trying n trying n trying... i'm jaded... and am getting insomniac... how to pass like tat??? :'(