Always happens when sleeping. Awake with tingling sensation in leg, one or the other, then proceeds to go inwards, sometimes cold sensation until I am completely paralyzed with extreme pain, extremities shaking. Feels like what I would expect it would feel like if I was elecrocuted. Fully alert throughout event. Usually lasts 15 to 30 seconds but last night lasted a couple minutes. 9-1-1 called but could not find a cause.