Hypnic jerk is a common experience among most people, it is the point when the muscles are trying to relax during the point your body is moving from the stage of consciousness into sleep, however the brain is well conscious and during that period it recognizes the relaxation of the muscles which is similar to that experienced during a fall, thinking you are falling, it tries to send signal to the muscles in order to kick them right up at which point you get startled and wake up. This is usually synchronized with a somewhat day dream of you falling.
Few moments ago I experienced an incident similar to that of hypnic jerk, however this felt more like a instantaneous deeming of light going into a total darkness, similar to the feeling of falling into the black hole, not that I know how that feels but theoretically speaking that's how it will possibly feel.
This feeling was more scary and the feeling as if you are dying at a rapid instant and conscious enough to know that it is actually happening. This happens to me when I am sleeping faced up, if anyone has similar experience or know a possible research going on this, the comment box is open for discussions.
