The biggest win of the early shift is that traffic is so *reliably* non-existant. People often suggest shifting late as if that's equivalent to shifting early. It's not even close. The thing is, traffic problems are not of instantaneous duration. An accident during rush hour (or a bridge opening or whatever) will cause lingering traffic for *hours* afterward. That means when you shift late, you either have to shift *really* late, or you have to have a pretty high probability of at least moderate traffic.
The traffic density ramps up very fast in the morning, reaches peak in 7-8 and then bleeds off very slowly. (The best data I've found is UW HOV study ; click the green boxes to download PDF's or go straight to Congestion Frequency ). Congestion before 7 AM is reliably near zero. Then it trails off gradually.
To shift late to really avoid traffic you have to shift to 11:00 - 7:00 , and even then you're going to be hitting way way more traffic than you would at 7:00 - 3:00 ; something like an accident on the 520 can easily make traffic bleed way past 7:00.
So, shifting early is awesome. No, not really. It means you have to go to sleep by 10 or so, eat dinner at 6-7, so you never get to see friends at night. If you do stay up late one time, it completely fucks you up.
The worst thing is that my body clock just doesn't want to adjust even with about 2 weeks of pretty steady early schedule. I wake up and I'm just exhausted, I'm yawning all day. I don't feel hungry at the early-shifted meal times, but if I don't eat I get woozy. So I'm just a bit miserable all the time.
I don't know how to live!!