I guess after acting tough all day they need to feel safe at night....BUT, I disagree with that graph, I dont act too tough, just a medium amount:P.....but everyone who comes to my room says they have rarely seen a person who sleeps with as many pillows as me.....I have like a pillow fortress on my bed:P......maybe I'm just an exception to your graph?
it clearly does not pass thru the origin. its a y = mx + C graph where m is the gradient and C is positive. so there are some men out there who while displaying toughness don't hug any pillows. they must be hugging their teddy bears.