What worked best for me is to use good ear plugs and sturdy intensely up until 9 pm. Then go to bed to get good sleep. Wake up early to go over my notes.
Getting good sleep was most important for me especial before tests. It’s important to feel good so you can think clearly. Sometimes you may not know the exact answer immediately but if you are alert then you may be able to scramble around in your mind and or on paper to get it or get close. If you feel exhausted from lack of sleep then you may just blow it off and settle for less.