Why can't I just sleep in?

Why cant I sleep in that much?
like, I can stay up until 3 in the morning and wake up at 9, and not be able to go back to sleep...
why is this?

If you live with someone else then most likely because they are up and banging around, or maybe because its light , You may beable to hear cars birds?
Stopping you from sleeping.. Im not really sure what else it could be.
Your body probably isnt used to the sleeping pattern.

Are you tired in the daytime? If you feel rested after 6 hours of sleep don't worry about it. Some people get by on 3 hours of sleep while others need 10. Everyone is different. 6 hours is usually enough for me though I usually get by with 5 during the week and sleep in on the weekends.

I have no idea if this will help ro not but I used to be the same way, I just started going to bed earlier and then waking up the usual time, if that doesnt work maybe try blocking the sun out of your bedroom window, whenever I sleep in my basement I sleep in till like 12 even if I go to bed early or late because there is no light down there. Get I darker curtian in your room and a darker blind. Please let me know if this helps, Thanks

If your used to sleeping 6 hours its all your body will allow, when I was in school id passout at like 1-2am and wakeup for class at 7. Now that im a bum waiting to start college im basically a damn vampire.

Sleep at like 9am, wakeup 6-7pm.
Your body adjusts :P

I get that too it's perfectly normal... and actually nice sometimes, because you can stay up llate doing whatever you want and still wake up at a good time, as long as you feel you have enough energy to last through the day it's fine. if you need to take a nap once in a while it's fine I do too. trust me, perfectly fine... but if you don't feel rested and fall asleep during class and such, maybe something is bothering you that you need to get off your chest, or maybe you have a sleeping problem, try talking to a doctor if this is so.