I JUST NEED SOME SLEEP

here I am at 3.30 am wide awake ... AGAIN!!!!! as I try to fall asleep, I get a weird feeling in my legs, I feel like I need to tense them and when I do I get a short burst of relief but about 20 seconds later I get the same sensation again. Someone please help me, it's been effecting me on and off for years and right now it's driving me CRAZY! Does anyone know what this is and how I can stop the damn thing