Why do I feel like my brain functions better at night?

I must be a vampire or a poor sleep cycle has my system outta wack. During the day I feel like not much is going on up there inside my head. I am often tired and not in the mood to socialize. Sometimes I just go through motions without thinking them through. I feel like a zombie. But at night I am full of energy and thoughts. Good jokes just spill out of me like diarrhea but oh cruel irony there is no one awake to hear my gems.