Yeah I was on a similar horrendous sleep cycle in college. Basically a ghetto uberman with too much drinking and 12 hour sleeps when I would crash and burn. Not healthy.

The biggest issue with that too is that you are forcing your body to sleep (ie: 11am-2pm) at a time when it isn't supposed to. It takes a lot of work to force yourself to sleep during the day. Blackout curtains and removing screens from your bed only help so much. Since both my sleeps are during the night now, it wasn't hard to fall asleep instantly and get a real rest out of it. I remember sleeping 3-4 hours during the day at college and I would wake up more tired.

It's all about building habits and training your body though. If you focus on cycles and routines, you can pretty much be ready for anything. Also getting into a routine for eating, what you eat, gym time, personal time, veg time, work time, etc help. Chaotic things like children and cocaine do not help this though. Since I do not currently have either, I am quite enjoying my sleep cycle now.