Big test in a week- tips on staying awake and alert?

I have a test in a week from today. It is very important and I only have two shots at ping so I can start on my graduate degree. My issue is I tend to get very tired during tests, and grow weary. Any tips on how I can stay alert? Caffeine has never affected me, the test is at 7:15 in the morning, we can not bring anything but water in the testing room with us. No food, drinks, etc. The test will take anywhere from 3-5 hours.