I remember those days some years ago when I used to wake up in the night with serious muscle cramps. But it just usually goes with the stretching of the leg. Though with time it just stopped and for years now I haven't felt it.

Thanks so much for providing basic explanations to these occurrences. Muscle cramps is a very common thing that most persons or those around them have experienced at one point or the other. So this information is valuable to everyone.