Why Do We Shiver?

For anyone who is trying to understand shivering, comparing it to sweating may be the best method. Shivering is sometimes described as the body’s natural, automatic reaction to a particular situation, just as sweating is. They happen to be exact opposites, however. When we sweat the body is usually trying to produce moisture that evaporates on the skin and cools us. When we shiver we are trying to generate and conserve heat.

Both are methods of maintaining body temperature in a healthy range. It’s all done automatically by our sympathetic nervous system. Our brain consistently keeps track of our body temperature, breathing, blood pressure etc. The body will trigger certain actions to keep these systems operating as they should. It’s also interesting to note that this automatic system that triggers a shiver isn’t the same as the one that we use to sense cold. We don’t feel cold on our exposed skin or hands and consciously shiver. But feeling this cold over a period of time may lower our body temperature enough to trigger the automatic response.

Our bodies and our brain sense cold differently in these two situations – consciously and subconsciously. One automatically tries to keep our body temperature around the accepted norm of 98.6 degrees no matter what the temperature of the room or outside air. We might feel the cold on our exposed skin and put on a long-sleeve shirt, jacket etc. to keep this cold from our body. But the automatic response is different. If the internal temperature of the body drops to a certain level that the brain senses as unhealthy or dangerous, the muscles start to contract and expand very rapidly, on a signal from the brain. This is what we feel as a shiver.

Because shivering involves rapid movement of many muscles of the body, more internal warmth is generated. This is necessary to keep the crucial organs of the body at a constant temperature so that they can function properly. If a person reaches the stage of strong shivering and constant chattering of teeth, this is a last resort for keeping the body warm. Our teeth chatter because the jaw muscles are expanding and contracting so quickly.

One of the interesting phenomena associated with body temperature is shivering because we feel chilled, even though we have a fever and our body temperature is not below 98.6. The brain may sense that the “set” body temperature should be higher and triggers the muscles into action. This explains the seemingly opposite conditions of being hot and feeling chilled at the same time.

So, in basic terms, our body shivers (we don’t do it consciously) so that it can maintain a constant, healthy temperature. If you feel this shivering it’s a pretty good bet that it’s time to go to a warmer place. It’s possible to get to the point of shivering even if we think we are dressed warmly enough. Inhaling cold air over a period of time can lower the internal temperature enough and set the shivering reaction in motion.