Right now I really have a lot of time for the day so I pretty much sleep 8-10 hours. I even sleep around 12 hours lol But I still feel drunk when I wake up :VAnyway, Just like you, I used to sleep around 4-7 hours when my life was still stuffed with lots of school work. Since my day isn't complete when I at least don't have a relaxation period (like games and stuffs) and I go home at 4 or 5 plus, homeworks and projects and stuffs takes 3 hours to finish, I tend to do relaxing around 9-12 and I wake up for school around 5-6. So yeah, 4-7 hours sleep. Man, I do not want to do it again. I'm like floating in mid air always when I sleep 4 hours.
lol I also sometimes don't sleep at all (Insomia) and I'll be like staying awake for 36 hours
But now things changed really, but it was hard to adjust back to normal time of sleep.
Anyway, did watch Mythbusters <3