Losing Sleep

I've realazied that my sleep schedual has been all kinds crazy lately. There are nights I don't go to bed until 4 am and others I'm in bed by 11 pm. The amount of sleep I recieve a night also varies. Some nights I get a good eight hours of sleep and other nights I get half that that amount. Depending on what I'm doing is usualy the cause of me losing sleep. Mass amounts of homework is usualy the reason for most of my late nights... most of them.