jimmy:

Thats interesting. Do you have to keep pushing later and later, or does a fixed offset give you this benefit?

For the same number of reduced sleeping hours, I feel much better if I'm pushing both bedtime and waking up time later and later each day. But even if I wake up at my regular time, the loss of the first few hours of sleep hurts far less than if I were waking up that much earlier, at least for the first two days or so.