I emailed my college academic adviser at 3:30 in the morning, what will she assume of me? That I'm an party animal? A crazed insomniac?

Both

This person posts continual pro child molestation questions over and over. When confronted he claims that it's just him joking around. It might be true if he only did it one time, but he does it over and over again. This indicates that he is indulging a fantasy and getting off on imagining himself doing this. Reporting him to Yahoo does no good at all so I encourage everyone to report him on either or both of the following links as a suspected child predator.

https://tips.fbi.gov/

http://www.missingkids.com/cybertipline

College students don't have normal hours. Or, at least, most of them don't.

If you make good grades and don't have any infractions, then she'll likely assume that you were up working on some paper. Or, of the two options you provide, she may assume that you have insomnia (though probably not crazed) and are just using the time to work. I wouldn't assume "party animal", since they are doing other things at that time.

Lots of people are night owls. Focus more on what you are saying.

Probably just another insecure college student.

If your adviser has been working in that capacity for more than 3 days, they should be used to it.