Well I had the same problem, but this is what I usually, one of the main problem areas is my forhead I usually don't even notice how tensed is so -
1. Try to relax your forehead after a while you will fell the skin sort of "slide" down a bit, it should stop the lid from opening.
I have noticed that if I trail the HI with my pupil I usually end up seeing my room.
2.Try to lie down in a comfortable position, it doesen't obligatory has to be your back your sleeping on. I find it much easyer to sleep sidewards.
3.And yes as Wildman wisely suggested try not to focus on it at all.
This helps for me.