why I can never sleep on the night of Christmas Eve

I've always wondered why it's so hard to sleep on the night of Christmas Eve. Ever since I was a kid, I would try all kinds of tactics to get Christmas to come sooner. I just couldn't wait to wake up my brother and sister and sneak downstairs to peek at our gifts. Of course, my mom and dad could always hear the “sneaking”, but they'd let us play downstairs for a while until we tired ourselves out.
The anticipation of Christmas morning always kept me up. Christmas eve felt like the longest night of the year. I remember figuring out when I was 7 or 8 that if I go to sleep, when I wake up, it'll be Christmas. Sleep was magic like that.
Unfortunately, from then on, my brain also figured out I was trying to circumvent the anticipation synapsis, and so whenever I would try to go to sleep early on Christmas Eve (I'm talking 5PM early), my brain would conveniently wake me up at about 10 or 11PM, and keep me wide awake through the night. I think I would catch a nap around 3AM, just long enough to give me that energy I needed for the morning's playtime.
At least that was my theory up until a couple of years ago.
I realize now that it was my brain keeping me up because Christmas Eve is the night that clowns feast on little children. My brain was telling me, “you can't sleep, clowns will eat you”.

And that, my friends, is the true meaning of Christmas :)