You need about 8 hours of continuous sleep for it to be the most effective. I mean, you're not going to seriously harm yourself doing what you're doing, but you will be more susceptable to illness, harder to recover, etc.
And the coffee is the same thing, not gonna seriously harm you, but in the long run, not the best idea.
I kind've have the same problem, I'm definitely a night person. I would love to stay up until 3 every morning and sleep until noon. But I am a student so I can't, and I've had to adjust my natural schedule.
Is there a way you could build in some quiet dark time during the evening before you go to bed? Know what I mean? A dark room or (I don't know where you live) a nice time in the evening, the sun goes down here around 6 pm now so it's easier for me.