Hello people, I'm happy to hear I'm not the only person who suffers with these scary painful cramps that come out of know where, and to be woken from sleep is just frightening. I am sitting here at 2:42 in the morning writing this, after suffering a cramp on my right inner thigh to scared to go back to bed incase it comes back.i haven't had a cramp in months, so I'm guessing mine is caused from dehydration as it is summer and I've been helping my daughter clean her house the last two days and been sweating heaps not drinking much then being in the aircon which also takes fluid from us has brought this on it lasted about 30 mins me with a hot tea towel wrapped round my leg I've been walking around my lounge room. I find that heat helps ease it a lot,  and I drink water , so now there back I'm going to drink heaps and take magnesieum plus put a container of water in my bed room while the aircon is on . And I've found if I can stay calm , and just keep walking around it goes quicker. Hope I've help someone.