Sleepy

it always seems when I have an easy time waking up in the morning for the rest of the day I end up being really sleepy but if I have a really hard time getting up I am still tired but not nearly as bad.what's up with that?!?!?also if i sleep until i can't sleep anymore for example on the weekends i still feel tired really tired and lazy but if i get only 6 hours of sleep(no more or less)i end up being pretty alert all day:\stupid REM cycle:P