I had this during pregnancy and DH gets this (and then jerks his legs around in bed - drives me bonkers!). Apparently it's called restless legs syndrome! A massage is a good idea, apparently walking a bit is supposed to help...I can't remember what else - I just jerked my legs around to give DH a taste of his own medicine! :P

ETA: Just remembered I used to clench the muscles and hold it, then release. I would do that til my legs got tired. Was helpful when I couldn't be bothered walking (though I usually needed to pee anyway).