You’ve just cleaned your teeth, you’re feeling minty fresh and ready to climb into bed. You take a sip of water, but the water is icy cold, and your next breath feels cool and crisp.

What has the toothpaste done to your mouth? And could this be a hack to help you feel cooler when you really need it?

Menthol, a natural compound that comes from mint plants, is the ingredient in toothpaste that creates the feeling of cold.

Menthol activates TRPM8 receptors on nerve endings in your mouth, which are the same receptors responsible for sensing cold. So, menthol essentially tricks your brain into sensing cold, in the same way that chilli tricks your brain into sensing heat.

It does so by binding to TRPM8 receptors and changing their shape, allowing calcium to enter and trigger a signal to the brain which is interpreted as a sensation of cold.

When you have a drink of water or take a breath of air with menthol in your mouth, the menthol spreads all over and more receptors are activated, increasing its effect.

The receptors are now open and primed to sense cold, so any liquid or air that is somewhat cool will feel even colder than it really........

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