I guess you were close to SP.
The problem was to keep your mind awake, try do some counting or thing of the alphapet and then an object on the letter or anything to keep the mind awake.
Most people prefer to lay on the back with the arms at the side of the body.
I found that putting the pillow a little bit futher down the back so it tilts the head a little bit further back (like when you're standing up and a going to watch the sky) make the swallow reflex go away a little bit more.
Good Luck