Dubya tea eff!?! Sleep deprivation is good for you?

First off, let me say that I am really frustrated. LIterally about 24-26 days out of a month I am extremely tired. If I go to bed at 10:30 or 11 and wake up at 6:45, I'm deathly tired. On weekends, with no alarm, I go to bed at 11-11:30, I wake up around 9:30-10 the next morning, and I'm really groggy the whole day. However, last week I had to tape our school's musical so I didn't get home until 11:30 or later each night, and ended up going to bed at around 12. I still woke up at 6:45 the next day, but for some reason, I wasn't tired at all and was even hyper. Then last night, I went to bed at 1AM, woke up this morning thinking it was 10 or 11, and realized it was actually 8:30. WTF?

So I guess this means less sleep is good for you (me)? But then why does it depend on when you go to bed? If I go to bed early, I sleep longer (even with no alarm) and I'm still tired. If I stay up late, I sleep less (again, no alarm), yet I'm oddly energetic. Can somebody please explain!? Thanks!