Why do you get "pins and needles"?

Pins and needles - is the name given to a tingling sensation you feel in your hands, feet, arms or legs when the blood begins to circulate again in does areas after being impeded. When you sit with one leg doubled up underneath you, you probably find when you try to stand, that your leg has "fallen asleep" and is numb. As the blood begins to flow again, the familiar tingling sensation will occur. Blood has been called "the river of life" and its circulation both distributes supplies to the body's cells and removes their waste. The body's five quarts of blood make a complete circuit of the system once every minute. Without this the cells would cease to function. A tourniquet a tie round a limb to halt the circulation, is sometimes used to stop bleeding from a wound into a vein or artery. But a tourniquet is generally loosened every 30 minutes and it should not be kept on for more than two hours at a time.