My DS7 was out of bed at 3AM with a big "OMG, OMG he came! he came!" I tried to put him back to bed twice. Once the adreneline kicked in, he was wayyyyyy too excited to go back to bed. Fankly, I'd be thrilled with 5AM. No one is allowed to open anything until everyone is together and I love that hour or so with my kids before they wake up daddy.
Christmas Day is long. We are at my inlaws for brunch by 11 and dinner at my parents by 3pm. My DS7 was beyond exhausted by 5ish or so last night and his behavior started to really go downhill. But, I can remember being the same way growing up. Frankly, I'll be really sad when I have to wake my kids on Christmas morning.