Why does my arm fall asleep when i put it in front of my head laying down on my stomach? is it normal? also why does my left arm feel like it wants to go to sleep when i fall asleep? should i be worried?

May be nerve problem: If an arm falls asleep, goes numb or tingly, or has changes in circulation, just in certain positions of the arm, there may be compression of the nerves and/or blood vessels to that arm. A primary care doctor, neurologist, and physiatrist (physical medicine & rehabilitation doctor) can help figure this out. Sometimes special x-rays are done to see if there is a problem of the nerve at the spine.