How come I get painful muscle cramps when I'm sleeping? Ones that rudely wake me up!?

I get leg cramps once in a while while sleeping (talk about a rude awakening). I know I'm not deficient in any vitamins, minerals or protein. Some of us just have weird bodies. I can often feel my muscles "gearing" up for cramps (mucles will twitch or just feel like something's going on) beforehand and then I drink quinine (actually tonic water which has quinine in it). I also cannot have the bedding I sleep under (blankets, top sheet) tucked under the mattress--my feet have to not be confined (so my foot isn't always forced into a pointing position), if I feel my legs or feet going into a cramp, I immediately jump out of bed and land hard on the leg/foot that is acting up which breaks the cramp. There are also over the counter tablets you can get that contain quinine. Make sure you are getting your daily requirement of vitamins, minerals, protein so you can rule those out though.