Each of us got a sleeping bag, two foam pads, and a polyfleece liner for the sleeping bag. At the start, we were briefed on cold weather injuries and the use of a radio. Major cold weather injuries are hypothermia, frost bite and trench foot. Hypothermia is when your body gets so cold your body pulls all the blood to the core to try to maintain life. Your blood vessels in your hands, feet and brain constrict.
Frost bite is when the skin freezes.
We were briefed on what to do if that occurs. I had never heard of trench foot. When your feet are kept wet repeatedly, bacteria grow and you can get an infection like gangrene and lose your toes, etc. This much more rare. To eliminate this, we were told to change your socks a lot.