What Is The Severe Pain Legs At Night?

Gd mrng sir, my mom is 46yrs old nw. When she goes 4 sleep at night suddenly her legs starts paining and unabke to coutrol she wil become asleep. This is every day problem for her. After 2-3 hrs she il b getng sleep. What is the reason behind this sir. Kindly suggest something. Watng 4 ur rply sir......