I used to get them actually late at night, eary AM - word of advice, dont jump up - woke up with a calf cramp so bad once I just started screming and hyperventilating from the pain, so made the mistake of getting up to try to walk it off.. passed out cold and cracked my head on the way down! (from the hyperventilating)... I found just staying in bed and rubbing the muscle until it stopped aching was the best therapy!