Hi F.,
Oh... I know very well what you are talking about since I've been there/done that with my twins. Mine are now "big kids" (9 yrs. old) But from what I remember is that things from social behavior, eating, sleeping, etc... went in phases. Although.... I am not promising you things will turn in your favor for sleep. (At least not for awhile...... mine are currently still sleeping at 9:30 am ! lol!)
You do have to remember that as children grow older they sometimes outgrow the amount of sleep they used to require. (Even if your little ones are going to bed at 8 and getting up at 6:30, that's 10 and a half hours of sleep.) Maybe not as much sleep as you'd want them to get since getting up that early to watch two active little ones can get quite demanding for a mom who's still trying to wake up herself. It seems as though you have a "new work schedule" for now. I would try to go to bed yourself by 10:00 so that you could get 8 hours of sleep before attending to your twins. I loved the mornings where I could actually feel awake enough to get out of bed 15 minutes before the "commotion" started to enjoy a cup of coffee in solitude! When I needed a bit more time to wake up, I would bring one baby back in my bed to cuddle, rub his/her back & put the music/t.v. on to wake myself up.
Here's a link that you might be interested in:
http://kidshealth.org/parent/general/sleep/sleep.html#
Enjoy your little ones. The days may creep by as toddlers, but the years will seriously fly by!
Happy Holidays,
J.