Do you change him at the dreamfeed? Our DS is nearly 8 mos, sleeps on his tummy or his side, and we found if we did not change him at the dreamfeed he would wake up with a leaky diaper 50% of the time. It's that darn big bedtime bottle. According to DH who does the dreamfeed, DS most of the time sleeps through the diaper change (wakes up once or twice a week, but then falls right back asleep).