My nearly 9 month old has suddenly started sleeping on his tummy. It started that he just slept on his side, and then started rolling onto his tummy. I'm really worried that it's not good for him and worried about his safety because he can only roll back onto his back occassionally. We used to go in and turn him back round onto his back, but most people kept telling us he would be fine and it could make him a light sleeper if we kept going in all the time. We were also told that if he wanted to turn back round and couldn't he would let us know. Really don't know what to do for the best and if the advice we have been given is ok. Any suggestions ??