This is the most common question, and it makes sense to ask that. However, it is truly impossible to answer, as some people tolerate cold better than others. The key is to aim for a temperature that evokes the thought, “This is really cold(!), and I want to get out, BUT I can safely stay in.” For some people, that temperature might be 60°F, whereas for others, 45°F.
Here is the key: the colder the stimulus (water immersion, shower, etc.), the shorter amount of time you need to expose yourself to the cold. One study showed significant and prolonged increases in dopamine when people were in cool (60°F) water for about an hour up to their neck, with their head above water. Other studies describe significant increases in epinephrine from just 20 seconds in very cold water (~40°F). The good news is that as you do deliberate cold exposure more often, you will be more comfortable in the cold at all times and can start to use colder temperatures with more confidence, just like exercise.
How Long and How Often?
Consider doing deliberate cold exposure for 11 minutes per week TOTAL. NOT per session, but rather, 2-4 sessions lasting 1-5 mins each distributed across the week. Again, the water temperature should be uncomfortably cold yet safe to stay in for a few minutes. You can do more, but this should be the minimum to achieve the benefits of cold exposure. You can do very cold, very brief exposures for adrenaline release too, but the 11 minutes is based on a recent study by Susanna Søberg that explored a range of effects and is a good solid, basic protocol for ongoing use.
Source: Huberman Lab
How Do I Endure the Cold?
Undoubtedly, during (or before) cold exposure, you will find your mind pushing back against the challenge. Your mind will say, “I really don’t want to do this,” even before getting in, or “Get me out of here.”
You can imagine those mental barriers as ‘walls.’ Those walls are, in fact, the effects of adrenaline pulses in your brain and body, which in this case is what triggers the eventual adaptive response. After all, if it were easy, then there is no stimulus for your body to change (adapt).
By maintaining top-down control of your reflexive urge to exit the cold environment, you will have successfully traversed that wall.
Challenge yourself by counting walls and setting a goal of “walls” to traverse (e.g., 3-5 walls) during the round of cold exposure. You can also go for time. Up to you. The advantage of the walls approach is that it carries over to other scenarios more seamlessly, as most of life’s stressors don’t lend themselves so well to merely timing the duration until it passes. It also enhances your sense of mind-body connection to do it this way.
What Should I Do After a Plunge?
The Søberg Principle based on deliberate cold researcher Dr. Susanna Søberg is: To enhance the metabolic effects of cold, force your body to reheat on its own. Or “End With Cold.”
Also, allowing your body to shiver may enhance metabolic increases from cold. Shivering causes the release of succinate from muscles and further activates brown fat thermogenesis.
Try this protocol to increase shivering, either during or immediately after cold exposure:
Don’t huddle or cross your arms while in the cold or after getting out. Also, don’t towel off. Let your body reheat and dry off naturally.
Source: Huberman Lab