Frustrating

So, why is it that my son insists on lying and staying up WAY past bed time. OK, this would not be so bad if it did not consist of stomping around and then pretending to be asleep. The sneaking is driving me insane.
Last night I put him to bed and we go up there and he is sitting on his bed with his tent and about 15 different toys, IN THE DARK! Is this really necessary? I mean I can understand it, I sit in my room thinking of 100 different things before I finally pass out a few hours later. But the difference between that is that he is 4! OK, he will be 5 in October but still! I don't understand.
Or his new found passion of sneaking downstairs while mommy is asleep and sneaking food out of the refrigerators and then stuffing it into his drawers. He hides drinks behind his television and even leaves food on his windowsill. so when he started waking up with bug bites, curiosity got the best of me. Now I don't avoid my sons room, I don't keep him locked in a dungeon but I don't always go in and look in all the corners or under the bed (although looking back, I think I should).
So, here I sit trying to figure out why on earth my son thinks sneaking and hiding food is just the way to go. Especially considering half the food he sneaks (grapes and apples) are foods I would let him have anyways. How do I stop him from sneaking down when I am ASLEEP in the morning? Do  dead bolt his door, because I am almost certain that could be listed under child abuse... so i am a little lost here. HA!