Dr. Susanna Søberg: How to Use Cold & Heat Exposure to Improve Your Health

This observational study from Finland with more than 2000 sauna bathers, they see that 30 minutes per session is, like, enough; and if you go above that, you don't get more health benefits out of it ... The healthy stress corresponds to, like, 10 minutes per session. It's not much, actually.

Studies have shown that if you sleep in 19 °C, then you will activate your brown fat and you will grow your brown fat, so you have more of it.

In the fall... you want to actually wear fewer layers, not bundle up when you go outside, so that you can prepare yourself for the cold of winter and be able to heat yourself up using your brown fat ... In the spring... you want to wear more layers in order to be a little bit uncomfortably warm so that in the heat of the summer, you're better at cooling your body.

You can go in the water for 1-2 minutes per session, but go up to 11 minutes per week in total. And for the sauna, my study showed 57 minutes in total per week. And if we also then divide it out on these 2 or 3 days... each day corresponds to 10 to 15 minutes.

If you submerge up to the neck, you have a heat loss rate of 11% from the body/core. And when you then also dunk the head, you will increase that heat loss rate by 36% .... That's going to increase your after drop... meaning that you are closer to hypothermia than you are if you just submerge up to the neck.

I think it's very important to think about the cold exposure and the heat exposure as something that then lowers the inflammation in the body. And if we can do that, we will have an open door for preventing lifestyle diseases.

You should get uncomfortable code. So, as long as you get uncomfortable cold, it's cold enough.

We shouldn't think about cold water and cold water immersion as something that is comfortable. It should be hard, because that's the point of it, right?

The more you... cover your body in the cold, which you would do in cold water... you will have a more potent activation of all your cold receptors in the skin. So, that one will definitely activate your autonomic nervous system more and rapid compared to going out in a t-shirt in the cold wind.

Men are more comfortable at 22 °C, and women feel comfortable at 24 °C.

The sense of urgency to get out of the hot sauna is a brain-driven mechanism. And so, the reason that people wear wool hats in the sauna is it actually lets you stay in the sauna longer.

Studies have shown that if you just put your hand in cold water... you can activate your brown fat just by getting a temperature change on your skin.

Women have more brown fat than men.

When you end on the cold, you force your body to heat up by itself; and that will require that you... keep your brown fat activated and also your muscles.

When you submerge into cold water up to the neck at 0 degrees—0 °C is very cold—you have decreased blood flow to the brain by around 30-40%.