Aside from the pile of gifts under the tree, how can you really tell if Santa came while you were asleep? Here are some traps you can set and clues to look for.
Step 1: Set up a test Leave a snack for Santa that your parents don't like. That way, if it's eaten, you'll know it wasn't just your mom and dad messing with you.
TIP: Put out grass for the reindeer. Most folks leave carrots, but reindeer prefer grass; that's why those carrots are usually only half-eaten.
Step 2: Look for white hairs Put a comb and mirror alongside Santa's snack. Santa likes to look good, and won't be able to resist giving his 'stache and beard a quick grooming -- the white hairs left behind will prove that he came while you were sleeping.
Step 3: Take a picture Take a few pictures of your living room before you go to bed. A big guy like Santa can't go bustling around with a sack on his back without knocking into a few things. The next morning, you'll be able to compare scenes to see if anything's been disturbed.
Step 4: Check for soot Check the presents for black streaks. Santa slides down a lot of chimneys on Christmas Eve; it would be impossible for none of that soot to transfer to the gifts.
Step 5: Feel for dampness Feel the floor for damp spots -- evidence of North Pole snow clinging to Santa's boots.
Step 6: Don't be discouraged Don't be discouraged if you don't find any solid proof that Santa came while you were sleeping. As someone who's been secretly delivering presents for thousands of years, Santa's gotten pretty darn good at covering his tracks.
FACT: The reindeer names "Donner" and "Blitzen" come from the words "thunder" and "lightning" in German.