7+ hours may not be solid enough sleep for you. 8-9 for many people is a bit more par for the course, though a lot of neuro research is coming out supporting the fact that regardless of quantity the "when" of sleep matters more. So, sleeping from 1 am to 10 am is much worse than 10pm-6am. Anecdotally, I had a friend who lost fine motor control of his trombone playing muscles in his mouth due to his sleep schedule and had to have a 10pm-5am sleep schedule for about 6 months before he could play trombone again. Its a special case but illustrates a similar point.