What Causes Numbness In Leg?

my right leg keeps falling asleep. It happens several times a night, in different positions. Should I be worried?



I'm a 53 year old woman and weigh about 115. I'm somewhat active but rarely "exercised" until a month ago when I started riding an excercise bike every day for 30 minutes - partly because I kept havingthis problem with my leg and thought it may be a sign of bad circulation that aerobic exercise would help.