If you do this a lot, you won't be happy with the results. I looked into this online and here are some things you can expect if you continually sleep deprive yourself:

- weight gain
- reduced intelligence
- ringing in your ears
- bags under your eyes and wrinkles
- impaired performance driving, speaking, answering questions, etc.
- immune system problems (get sick easier, etc.)

In general this is a really bad idea. Plus what if you fall asleep during the exam or can't think straight during it?