Is this natural for a male cat? ?

Does anyone know why my male and neutered cat ' humps ' my leg when I lay down to go to sleep? He did it to a blanket while he nursed the blanket as a kitten and I thought that sure it's weird but I just got him he wasn't even a month old! but then I just hid every soft thing in sight and he stopped. Later he was neutered but every night I would lay down and almost fall asleep but then he comes in and starts kneading my shoulder. And yes, I have shut my door but he just scratches and yowls at it and runs around the hallway meowing as loud as he possibly can! I started spraying him with water and it worked for about a week. Sooner or later he's a year old and he's stopped everything he used to do, but he has started a new thing where he humps my leg whether I'm sitting down watching tv, doing work, or falling asleep!  So does anyone know why he's doing that or more important, how to stop it? Thanks for whoever answers.