Thanks for the DSPS article. If left alone, my natural sleep-time is 4-6am. I've never successfully reset it for any long periods of time. I can force it for a few days (like for work when I'm forced to an 8-5 schedule), but will immediately return to my usual times on the weekends. If I don't get to do that on the weekends, I become a very grumpy Moni -- even if I'm still getting 8+ hours of sleep.