Are you kidding? We regularly didn't get to sleep until after 1 in the morning in college. College is the last great time that you get to enjoy that freedom. I wouldn't shoot it in the ass just yet. I still act spontaneously, however, the requirements of my job force much more planning. This doesn't imply that I was ever a person who was late or unprepared. I simply planned for random things to happen in college.
In all honesty, the next time someone calls at midnight asking if you want to come over...maybe you should go over. You only get one pass through that time of your life. You don't get to go back.