It happens to me all the time. Before we moved to an apt., I would get up by 6:30-7AM, make my tea and bagel, then I would either read or work on a project in my sewing room. I would be asleep by 10 PM. I complained that my husband stayed in bed until 10-11 AM. Guess what, now I stay up until after 11 PM, wake up at 2 hour intervals all through the night, not really getting into a sound sleep until 3:30 AM. Then I would wake up at 7:30 when my friend called on her way to work (only time we can talk), feed TJ the cat and go back to bed and not get up until sometime between 9-10:30 AM. But guess what? Now my husband wakes up when I do - no quiet time to pretend I'm all alone. There must be some kind of tremor in the force that has us all messed up with our sleep. I know exactly how you feel.