Cold Water Therapy is a practice that’s gaining popularity among people who are into health and fitness. It can take the form of outdoor swimming in chilly lakes, icy showers and dunking your body in an ice-cold tub, and it’s been used for a while by athletes looking to reduce muscle soreness after intense workouts.

But what many may not know is that cold water immersion also has a whole host of other benefits. In fact, it can help with depression and anxiety and even boost your immune system.

The reason for this is that it triggers a number of the body’s natural healing processes and nervous system responses. It can be a great way to kickstart your day and even improve your mental health and mood, and it’s certainly not as harsh as some of the other things you can do that will have similar effects.

Specifically, when you’re exposed to the cold, your blood vessels constrict, and then they’ll slowly start to expand again once you’ve come out of the cold. This is a process called vasodilation and it causes your blood to pump faster, providing more oxygen and nutrients throughout your body.

This process also helps your muscles get more flexible, which can decrease the risk of injury and help you stretch further in your workouts, per Cleveland Clinic. And it can improve your overall mood as well by activating the sympathetic nervous system and increasing your levels of norepinephrine, a neurotransmitter that boosts brain focus and releases endorphins to make you feel happier.