According to this yahoo article, graveyard shifts are a "probable" cause of cancer.

I'm glad that I don't work that shift anymore...who knows though, if I get fired, then maybe I'll have to do that again. But yeah, the people who I saw that worked that shift at my old workplace looked really old compared to people I saw who worked during the day.

I guess maybe I need to take better care of myself and not stay up too late anymore...