[Madmartigan21]

Here's a random thought. I don't usually play during the day so this a "theory" at best. Perhaps more of the people who play during the day are doing so out of boredom. They're people who have cash and some time to kill, but don't play very often. They have the day off from work or are at work and it's slow. They aren't trying to play "serious" poker. Where as many of the people who play at night set aside that time to play poker. They play regularly and have a better understanding of the game.