I have never seen mine lay out like that. If they were over heating they might lay like that. If this chicken was attempting to take a dust bath, they can roll around like this one looks like it is doing. I am not sure about sleeping like this being normal. LOL An old bird might lay out if their legs were not as strong as they used to be. Although, I do have a Lovebird that will lay on her back in my hand and sleep like she is dead. LOL Hmmm....Maybe I should post a pic here for this thread..LOL
He's only 4 months old and he sleeps like that in the house too with the air conditioning. He's done that since he was a chick. I've stopped having heart attacks a few months ago lol