Why does my cat move sleeping spots throughout the night?

My cat has a system of sleeping that I've never had another cat do. He doesn't really like to cuddle. (As an aside, he likes to be held and cuddled, but he refuses to cuddle when I'm sitting or lying down.) He likes to be near me, with maximum one point of contact when I'm sleeping. What I don't understand is where he sleeps. When we go to bed, he always starts next to my feet. At some point in the night (unsure when), he moves up to sleep next to my chest or head. I know there's different reasons for cats to sleep by your feet vs by your head, but why would he switch between them, always in this order?

Tl;dr Why does my cat prefer to sleep at my feet in the beginning of the night and near my face in the morning?