I had the same problem when i was a freshman. In high school i was so used to going to bed around 10pm and waking up at 6am.
Even though i had 8am classes freshman year, going to bed early was impossible for two reasons. 1.) parties
and then 2.) once i got my priorities in line, our next door neighbors were so freaking loud that we had no choice but to go to sleep at 3am. Whether i have a 8am class or not, i always have to take a shower and have enough time to calmly find something to wear, fix my hair, brush my teeth, put on makeup and eat breakfast. Therefore, i would go to bed at 3am or later and then have to wake up at 6:30am.
Around the hours of 2-3pm to about 5-6pm, my roommate and i would catch up on our sleep!! And yes, i would nap for about 3 hours because i would only sleep 3hrs at night! It was awful!!
Taking nyquil does help, but i would suggest doing it only for those once in a while nights where it is imperative you go to sleep within 30 minutes. NEVER taking sleeping pills!!
Fortunately, now that I am living at home, i dont have that problem! I normally study best at night when everyone in the house is getting ready for bed, already in bed, or just watching television. I also dont have any problems going to bed, and i usually always wake up about 1-2minutes before my alarm goes off in the mornings. When the alarm wakes me up, its a good indication that i am tired!
I even wake up pretty early on weekends, so my sleeping schedule is not off track come monday morning!