Why Isn't He Sleeping???

For the past couple weeks, Jimmy's sleep patterns have been insane!  Toward the end of the summer, we were in a great groove: he would take a short morning nap, a long afternoon nap, go to sleep at around 9:30, wake up once during the night to eat, and then sleep until about 8:00!  It was great.  Now he goes to sleep anywhere from 10:00-11:00 (or tonight it was 11:30...), take one afternoon nap, and then wake up once or even twice to eat at night!  AHHH!  I don't know if he is having a growth spurt, but somehow I don't think so.  His growth has slowed down considerably since birth.  It's possible that it could have something to do with his desire to get better at standing.  I keep waiting for the day that he figures out how to cruise.  Maybe once he does he'll go back to being a better sleeper.  One can hope, anyway!!