Cold Calm

If you need to calm down, you might try splashing some cold water on your face.

You’re thinking: that seems paradoxical! After all, cold water tends to wake you up and irritate you, not calm you down. What’s going on here?

All around your nostrils and eyes, there are special receptors that you can trigger with cold water. These receptors can cause your heart rate to slow down considerably, which can involuntarily calm you down a bit.

This reaction is called the Mammalian Dive Reflex, or MDR for short. Like the name implies, it centers around the way mammals plunge into water. Since mammalian origins center around water, it’s perhaps no surprise that we’re all encoded with some type of MDR.

It’s also probably no surprise that aquatic mammals like dolphins, whales, and seals have the strongest Mammalian Dive Reflex. After all, they might need to spend hours underwater chasing after a potential meal, or being chased by one. Being able to dive deep and use less oxygen can mean surviving….…