ASD Child Sleeping with pillow on head

Hello,

My almost 9 year old son is ADHD/ASD. I believe the pillow on his head is relating to ASD. 

Every night my son will sleep in the same position, surrounded by his toys in the exact same spot every night and make me lay a pillow over his face, now this pillow has to be in the EXACT position and I am there for about 45 minutes up to an hour getting this pillow on him in the right position for him to be able to sleep. This also happens if he wakes in the night (which he often does if the pillow has come off him or he needs the toilet or a night terror, the list goes on) then I have to stand there again for a lengthy piece of time getting this pillow exactly right. 

Does anyone else’s child do this or similar to this or does anyone have any tips or ideas to try as I am losing patience and sleep!! 

thanks