We bought this because my 4 month had severe flat head syndrome and he only wanted to sleep with with the back of his head down. We'd turn it and he straighten it back out making his flat head flatter and even more bald. After 3 weeks of using this, his hair has grown back and his head is rounding out. He's so active now he gets away from it at night, so we use it only during the day when we can watch and make sure he doesn't get it over his face!