Maybe sone GF/BF that wants you to be successful. The person is a sympathizer and knows all your sites so rotates and clicks away in the morning before going off to work or school or something!
I wish I did have a bunch of sympathizers. lololol Today it was the same really. 90% of all clicks by noon. So freaking weird!
I like immortality's suggestion... Maybe everyone surfs early, than goes and empties crawfish traps all day. ;-) Just kidding... Maybe you could really "dig-in" to the Awstats and server logs and see who or where your morning "clickers" are and where they come from for an idea???
He does have a fine point (ads crap out later in the day), but that can't be it. Too many niches for that to be right. Also, the main site has the same advertisers on it all day long (and night too). This is a real mystery to me. I wish I could figure it out. Good idea about looking at stats. Let me give that a try. Emptying crawfish traps during the day? lololol Good one!!