Oftentimes they lower the medications for extended monitoring so they can get better results. But it sounds like you are still having episodes so you might have something show anyway with a sleep deprived EEG. (I'm considering asking for my daughter to have another EEG since she is still having seizures, maybe there is something else worth noting that would help decisions regarding her treatment).
Some doctors often don't believe it is epilepsy if an EEG is clear even though they should know better, so a neurologist who isn't aware of that is not the best doctor to treat you. I would hope your doctor was just trying to reassure you and not give you the fussy details. Our daughter's surgeon warned us EEG had limitations when the first EEG was clear and I said something was wrong. He specializes in epilepsy surgery. Pretty sure Sue (Porkette) had seizures only show up on iEEG (not EEG) if she wants to give you a direct experience. Brief non technical write up mentioning there are limitations at
http://www.webmd.com/epilepsy/tc/dia...topic-overview