Sleeping behavior

Why is Colton waking up again? I put him down at 9pm and wish that he could sleep till 8:30am or 9am the next morning. He was up at 5am. He opened his door and called ” ma ma…”, then laid down in his bed sucking his thumb till almost 6am. Then he asked for milk, so I gave him his bottle then I left him alone. He stayed quite till 7am and he was fully awake. This is not fun at all!

Carol