It's a refreshing way to start the day. Here's my deal:

I've got 16 month old twins and my riding time is precious. Lucky for me that the kids are champion sleepers and they'll usually sleep until after 7am. So I'm up every morning at 5:30, a little cereal and a big mug of java, and I'm out the door before 6. I'll ride a solid hour, walk in the kitchen door, warm a couple of bottles, change a couple of diapers, and hit the shower while the kids play and my wife grabs a few more Z's.

Then I'm dressed, and back on the bike by 7:50 for my super-mellow 4 mile commute to the office.

Sometimes I get a little sleepy in the mid-afternoon, but I think that pretty much applies to anybody who gets up at 5:30, whether they ride a bike or not.