About infrared radiation

Fever is a reaction to invaders. When your immune system is fully charged up against a disease, it requires a lot of energy to produce fire arms e.g. white blood cells, antibodies. In that case, the body basic metabolic rate will increase to cope with the production. All your cells now work extra hard, and excess heat is produced as a result.

Another theory I heard from a TV channel ?National Geographic? is that higher temperature is unfavorable for bacteria/virus multiplication. That means they grow fastest at 37C and slower at 40C. So I guess it make sense for Chinese medical practioners to let you fever, or even tell you to go to bed with a thick quilt to 焗一身汗. That temperature slows down the growth of virus and at the same time draws out metabolic waste in sweat, and you will get well sooner by running out the natural course of the disease.

Although lowering down the temperature seems not in your favor, there are cases where the high temperature will be detrimental, say to infants and young children, because it may damage the brain. Paracetamol is necessary in these cases.

When a person get fever, the blood capillaries on skin dilate to release more body heat. One way to release heat energy is IR.

Hot object will emit infra red radiation. The hotter the object the higher the intensity of raditation.