Thanks everyone for your answers and reassurances, I feel much better.  And actually, I have a knitted baby blanket that I wasn't using because it didn't look like it would keep a baby warm. I'm glad to now have a use for it, as my grandmother made it for him. I've just got to wash it half a dozen times first as she has lots of cats!!

My niece does this too with her favourite blanky as long as it is not a heavy blanke and the cellular ones are best then it should be fine.

I wish I could get mine to stay under the covers!!! lol.  At his age, the risk of suffocation is minimal.  He has already learnt how to save himself, so I wouldn't worry too much.

my son started doin that since he was 5 months old i think its a comfort thing cause my son is almost 3 now and everytime he goes to sleep he pulls the blanket over his head just be sure to check to make sure atleast the nose is out and the eyes are covered there shouldnt be no worries nothing happened to my son and everybody had a fit cause i wouldnt remove the blanket but my baby is still here lol good luck  the baby will be fine.

Both mine did this, so I got them breathable knitted/woven blankets - preferably cotton.  My son still has his special blanket - it is "bubby" and goes to bed with him every night.  If they can breathe through the blanket, my only worry would be if they wrap it around the neck, so I'd just keep an eye on that.  The worst thing for me was when well meaning people would uncover their faces down the shops and they would wake up!

my son does the same thing. i used to worry that he would suffercate but i found he likes the blanket on his head. plus he pulls the blanket if his face is cold or the sun is getting on it.  i think its a comfort thing.