Because of fail-interpretation you project and identify this feeling with your subtle body and now you let behave the subtle body as if it was heavy. Well, I close my eyes, I see the ceiling through my eyelids, and fell 'in the oobe state'. I do not panic by these episodes at all. I actually try to investigate a little further, and try to move around, but this is impossible. Getting up from the bed is incredibly hard, because of how heavy I feel.
Every movement is sloooooow, and almost against a force.
Very strange, and frustrating. One very often has this feeling in the late morning in the short awake phases while still lying in bed. It is the same feeling as you try to produce by will in hypnosis or autohypnosis. The sleep paralysis is quasi obligatory for the REM sleep and nearly always observed in the first OBEs, but may vanish later on with greater OBE performance. The ASP can be observed as well in the OBE prestage, if the starting OBE process is interrupted by fear or any other reason.