Cat owners know that sleeping can sometimes be a challenge. Cats, by nature of their personality, think that they rule the world. Thus their sleeping behaviour is completely rooted in what they feel like doing on any given evening. There is not need to try and control them - it will fail.
These pictures show some of the favourite cat sleeping positions. We're lucky I guess, our cats do not bring us dead things (although there have been a few icky barf situations) nor do they often sleep ON us. The rest we've all experienced. Of course, with two cats we often experienced two completely different sets of behaviours an evening making for a challenging night!