Blame your hardwiring.

At night the morning person may want to go to bed early and not be in the mood for conversation. Whereas the night person may be eager to stay up late and eager for conversation. In the morning, the morning person's being awake, busy around the house, and being cheerful may annoy the night person, who either wants to sleep later or is awake but wants peace and quiet.

Scientists isolate the genes associated with "morningness."

A surprising downside to being a night owl