@SarahGen-- There is a chance of someone who experience seizures to have a seizure during the EEG if he or she is sleep deprived. This is why a sleep deprivation EEG is done, to look at how the brain is working during the seizure and which part of the brain is specifically associated with it.
I've had several sleep deprived EEGs done. When my medications don't work well, my doctor has me get one to adjust/change my medication accordingly. I've even had one where I was asleep during the test.
It can be difficult to stay up an entire night, but it's worth it. A sleep deprived EEG can say a lot about what's going on in the brain.