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How cold?

This is the most common question I hear, 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.

Ice bath, cold shower, or cryo?

Most of the studies use ice baths or cold water­­­ immersion to the neck. Those are best, but cold showers can work too (and are more accessible to most). Cryo is very expensive and harder to access and not subject to much variation in protocols, so it is not considered here.

To Increase Energy and Focus

Deliberate cold exposure causes a significant release of epinephrine (aka adrenaline) and norepinephrine (aka noradrenaline) in the brain and body. These neurochemicals make us feel alert and can make us feel agitated and as if we need to move or vocalize during the cold exposure. Cold causes their levels to stay elevated for some time and their ongoing effect after the exposure is to increase your level of energy and focus, which can be applied to other mental and/or physical activities.

Building Resilience & Grit

By forcing yourself to embrace the stress of cold exposure as a meaningful self-directed challenge (i.e., stressor), you exert what is called ‘top-down control’ over deeper brain centers that regulate reflexive states. This top-down control process involves your prefrontal cortex – an area of your brain involved in planning and suppressing impulsivity. That ‘top-down’ control is the basis of what people refer to when they talk about “resilience and grit.” Importantly, it is a skill that carries over to situations outside of the deliberate cold environment, allowing you to cope better and maintain a calm, clear mind when confronted with real-world stressors. In other words, deliberate cold exposure is great training for the mind.

Enhancing Your Mood

While not true of every stress, cold exposure causes the prolonged release of dopamine. Dopamine is a powerful molecule capable of elevating mood, enhancing focus, attention, goal-directed behavior, etc. Even short bouts of cold exposure can cause a lasting increase in dopamine and sustained elevation of mood, energy, and focus. Listen to Episode #39 to learn more about dopamine’s role in the body.

Metabolism

In the short-term, cold exposure increases metabolism as the body has to burn calories to increase core body temperature. The total calories burned from the cold exposure are not that significant. However, the conversion of white fat (energy storage) to beige or brown fat (which are highly metabolically active) can be beneficial for:

1. Allowing people to feel more comfortable in the cold (i.e., cold adaptation)
2. Triggering further and more sustained increases in metabolism

Of course, calories in (consumed) versus calories out (metabolized) or “CICO” governs whether you gain, lose, or maintain weight. There is no escaping the laws of thermodynamics.

A Solid Basic, Science-Supported Protocol

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 that explored a range of effects and is a good solid, basic protocol for ongoing use.

The Huberman Lab “Counting Walls” Approach

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.

Shivering and The Søeberg Principle

The Søeberg Principle based on deliberate cold researcher Dr. Susanna Søeberg 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. Admittedly, this is tough. Unless doing deliberate cold exposure on a hot sunny day, admittedly, I prefer to take a hot shower and towel dry after cold exposure, but I am no doubt limiting the metabolic effect by doing that.

Physical Recovery

A meta-analysis of cold-water immersion effects on recovery found that cold exposure can be a highly effective recovery tool after high-intensity exercise or endurance training. Short interval (< 5 mins), cold water immersion demonstrated positive outcomes for muscle power, perceived recovery, and decreased muscle soreness (in part due to a reduction in circulating creatine kinases).

The problem is that cold water immersion (but not cold showers) can limit some of the gains in hypertrophy, strength or endurance if done in the 4 hours or so after training. It’s better to wait 6 to 8 or more hours until after training, or do it before training UNLESS your goal is simply to recover without adaptation (for instance, when in a competition mode and not trying to get better, stronger, etc.)

Day or night?

After cold exposure, your body heats up—yes, HEATS up—for reasons discussed on the Huberman Lab Podcast with Dr. Craig Heller from Stanford. Body temperature increases tend to wake us up, whereas body temperature decreases tend to shift us toward sleepy states. Thus, I suggest using deliberate cold early in the day and not too close to bedtime. Sometimes it’s better to do it late than never, but not if it perturbs your sleep. If deliberate cold affects your sleep, try doing it earlier in the day, or not at all.

Increasing the Resilience-Enhancing Effects of Deliberate Cold Exposure

Staying completely still while in cold water allows a thermal layer to surround your body, ‘insulating’ you from the cold. To be most effective as a resilience training tool, move your limbs while keeping your hands and feet in the water. That will break up the thermal layer and you will experience the water as (much) colder than if you stayed still. This is also a good way to increase the potency of a cold stimulus without having to make the water colder. This is akin to slowing down the movement of a weight lift to remove reduce momentum and provide more tension on the working muscles.

Best wishes,
Andrew

Disclaimer: The Huberman Lab podcast is for general informational purposes only and does not constitute the practice of medicine, nursing or other professional health care services, including the giving of medical advice, and no doctor/patient relationship is formed. The use of information on this podcast or materials linked from this podcast is at the user’s own risk. The content of this podcast is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Users should not disregard or delay in obtaining medical advice for any medical condition they may have and should seek the assistance of their health care professionals for any such conditions.