What is a key sign of severe hypothermia?

A key sign of severe hypothermia is the absence of shivering and an inability to walk. In the progression of hypothermia, when a person reaches a severe state, their body loses the ability to generate heat effectively, leading to a cessation of shivering. Shivering is the body's natural response to cold, as it generates heat through muscle activity. When this response stops, it indicates a significant drop in core body temperature. Additionally, the inability to walk may occur due to muscle stiffness and decreased motor function, which are direct consequences of the body's attempt to conserve heat as it becomes critically cold. Recognizing these signs is crucial in wilderness medicine, as they signal a life-threatening situation that requires immediate attention and intervention.