Years ago, when in bed, I sometimes got very strange, uncomfortable. very unpleasant feelings in my legs. Like when you hit your funny bone. My legs also jerked involuntarily. My then boyfriend told me to lie on my front like a seal ( can put cushions under my forearms), and to bend my back, backwards till I felt pressure in my lower back, i.e. below the waist. This pressure being the most important part. Hold it for 2 or 3 minutes. I did it and was then fine. And for 20yrs it has worked 100%. However, though it worked for me, it may not work for anyone else, and as it is a physical manoeuvre, I would suggest that anyone thinking of trying it, checked with their Dr/G.P. first, in case it causes more problems. In the first instance, however, If I sit up straight, at all times, all day, on chairs, the sofa, or when reading in bed, with a small firm pillow in the hollow of my back, I don't get it. So this could be tried. I used to be a nurse, and I am very conscious of responsibility, so anyone needs medical advice before the back bending, as I am only saying it worked for me.