Pamela Gay has written a nice post on what it was like to be in grad school, complete with being a night owl. She observed far more than I ever did; using Hubble meant waiting for the data to be delivered (on tape! by mail! or by me driving up to the Space Telescope Science Institute and picking it up!) and not needing to stay up all night. Though, for my Masters, I did observe every night for two weeks in a row, inducing almost literally waking nightmares... but that's a tale for another day. Go read Pamela's. As usual, she speaks truth.