I like the anonymity of night. I can work tirelessly, without concern and disruption of interludes that daylight brings. During the day you're preoccupied (or too busy pretending not to be preoccupied) keeping tabs on the clock as it ticks to lunch time. Then your senses fail after a heavy meal. Perhaps indulge in a caffeine pep, or energy drink to prop you up the rest of the afternoon. Wait in your windowless cube until the seconds turn to minutes turn to hours turn to another day on your hamster wheel.
The silence of past midnight is all encompassing. The world is quiet. Your mind is free. To create, or to vegetate. The reasons are all your own.
I can find all the reasons to stay up all night. The missing piece of the puzzle though, is finding all the right reasons to wake up earlier in the morning. :P