How can i know where i put my hand when i sleep. You didn't know what your "hand" can and would do when you fall asleep. If you ask what your feet do at night during sleep to people who are sleepwalking you would find strange answer
I sleep hanging upside down so my hands are hanging below, but technically they are raised above my head
Depends. If it's too bright in the room where I'm trying to sleep, hands above to cover my eyes. Usually it's down though. Either between my legs, on my stomach, or just hanging at the side.
...you don't want to know... My sleep posture is pretty standard, left hand under face, right hand between knee in foetal position. It's the posture you use to sleep in to prevent your rifle from being stolen. You curl up around your rifle, barrel up, magazine facing out. Left hand around the flash suppressor to prevent it from being unscrewed, right hand is around the empty mag to prevent someone from popping it out and running away with it. It's incredible what training can do, even 30 years after the fact. And I don't move while sleeping. Proven when my squad couldn't find a place to sleep and had to sleep on motorcycles with their kickstands down. If we had moved, we would have woken up on the ground. We didn't. Training.
Usually one hand under the pillow, with my head resting on it. The other... it varies. In any case I usually sleep on my side, taking some variation of the recovery position.