I have been dx with Restless Leg Syndrome & Periodic Limb Movement........Difference is RLS is when you are awake, and PLM is when you are falling asleep and are asleep and your arms & or legs "jump" or twitch. I learned I never get past stage three, I awoke 197 x's (don't remember it at all, but you only develope a memory after being awake for 60 sec), my legs move 57 x's in one hour!! No wonder my legs have been killing me....they are having a party while I am trying to sleep!! Thank goodness I do not have sleep apnea...but lack of getting to REM (stage 5) of sleep can cause memory loss, hormonal problems, even weight gain. Just thought I would share my experience.