I Am 72, Male, In Generally Good Health, 160#, 69"

I am 72, male, in generally good health, 160#, 69" tall. During the day I am reasonably active, go to yoga with my wife 3 times and week and do some weight training once or twice a week. During the days I feel fine. At night I go to sleep easily but wake up after a couple of hours with lots of muscle pain, leg and foot cramping and severe muscle tightness. Thats it - when I'm up I'm fine. When I lie down for a while I stiffen up and hurt so bad I can't sleep.