From time to time when I am lying in bed I will get a painful leg cramp. When my children were younger, they once witnessed me suddenly start writhing upon my bed yelling "Charley horse! Charley horse!" This caused them some distress and moved one of them to tears as they could not understand why I would call out the name of a puppet from Lamb Chop's Play Along.
I had noticed that many of these leg cramps were initiated by a morning stretch in which I would extend my toes. I now know that I can instantly relieve a cramp when I feel one initiating by pointing my toes up and extending my heel instead.