5 month old has rolled onto his stomach - will he be okay?

[Serenity05]

My DS is 5 months old and a terrible sleeper. He's always been nearly impossible to settle unless he's in my arms or on me. He had reflux and colic up until around 15 weeks although both have pretty much gone now. If I'm lucky I can get him to sleep in his cot (he's in a Next2Me) for a couple of hours at the beginning of the night but then I end up bed sharing with him.

He has recently mastered the art of rolling from his back to his stomach and about half an hour ago I watched as, in a restless half-asleep state, he rolled himself over and immediately settled. He's been sleeping peacefully since.

I don't want to move him back and wake him up but is it okay to leave him like this or is he too young?

Brilliant, thank you. He's curled himself up into a ball on his side now - the same position I like to sleep in!

And good point about the bed guard, thank you.

At 9 months, we've finally figured out that DD hates to sleep on her back and prefers her front! Really wish I'd figured that out a lot sooner. If he can roll and keep his head up unsupported, I'd say it was fine.

My DD has slept on her front dice she was about 5 weeks old she suffered with terrible reflux, and in the end, my dr said that even though it goes against safe sleep advice, try putting her on her front (watching her the whole time obviously!) and she if she "relaxes"......not only did she relax and not throw up, she fell asleep and had the first good nap she had ever had. She has slept on her front day and night ever since - she's almost a year old now.
If your son has rolled himself into that position and is comfortable then it's fine everyone loves restful sleep!!