Why do we shiver when we are cold?

THAT'S THE WHY: If you have been out for long periods in the snow recently and found yourself starting to shiver, you may have wondered why we sometimes start to shudder beyond our control when the temperature drops.

In short, it’s a mechanism by which humans and other mammals can literally warm up by twitching muscles quickly to generate heat.

Keeping a tight rein on your temperature is important – the biochemical reactions that keep your body working run best when your core temperature is close to 37 degrees.

If your core temperature dips too low, those biochemical reactions will function poorly and, in severe cases, it could lead to serious injury or death. So we have a battery of tricks and responses to regulate body temperature, and shivering is among them.

Temperature-sensitive nerve endings in the nervous system monitor the skin and core. When warnings of cold start coming through, the brain takes the brakes off particular motor signals and muscles start to twitch, releasing heat as a by-product.

Other anti-cold strategies can include restricting blood flow, closing skin pores and speeding up your metabolic rate.

Such “homeostasis”, or keeping balance in the face of environmental change, is far too important to be left up to your conscious control, so your nervous system and a region of your brain called the hypothalamus are keeping watch for and reacting to changes.