I know this sounds a bit silly but my 5 month old DD (who can't yet walk, obviously, but is starting to creep on her belly) has started turning over during naps after being placed on her back and is trying to creep around: the first couple of times she did it I thought she was just awake and not napping but on investigation her eyes were closed and she was quite clearly doing it in her sleep. Obviously this is worth keeping an extra eye on in order to prevent her hurting herself, but this aside does this mean there's anything to worry about developmentally/cognitively?