A7. To boost up immune system.
If common cold viruses invade into the body, they multiply in the cells of the throat. White blood cells eat the viruses and analyze the information of the virus and inform it to the brain through cytokine. The brain orders to raise the body temperature. If the body temperature raises, the immune becomes more powerful. If the body temperature becomes over 40 degree C (104 degree F), viruses die.
To prevent heat going our from the skin, blood vessels under the skin becomes narrow, leading to less blood flow, and sweat glands becomes narrow, leading to less sweating.
Another way to raise the temperature is shaking the muscles. That is the same as when it is cold, our body naturally moves the muscles to raise the body temperature.
After defeating the viruses, we sweat to lower the body temperature. That means sweating is a sign of recovering from a cold.
A8. To make immune system concentrate on a fight against viruses.
Our body uses all the energy for immune system to fight against viruses. Sluggish feeling or general fatigue is a sign not to use the energy for moving the body. That means our body requires rest.