"DONE CORRECTLY, DELIBERATE HOT AND COLD EXPOSURE (TEMPERATURE THERAPY) CAN POSITIVELY AFFECT BRAIN AND BODY HEALTH WHILE INCREASING METABOLISM, PROMOTING FASTER RECOVERY AND INCREASED FAT LOSS." 

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- DR ANDREW HUBERMAN

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HOW COLD?

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 15°C, whereas for others, 7°C.

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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 (15°C) 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 (4°C). 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.

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HOW HOT?

The general guideline to start heat stimulus: temperature must be between 80°C and 100°C for 5-20 minutes, 2-7 times per week – later in the day is better to activate cooling mechanisms and assist with sleep. Find what works for you: choose either higher heat intensity and shorter bouts, or lower heat intensity and longer bouts – but always between 80°C and 100°C.

 

Make sure you’re replacing the water you lose in the sauna – drink at least 500mL ounces of water for every 10 minutes of sauna use.

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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 vocalise 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. 

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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 centres 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.

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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.

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METABOLISM

In the short-term, cold exposure increases metabolism as the body has to burn calories to increase core body temperature.

 

However, the conversion of white fat (energy storage) to beige or brown fat (which are highly metabolically active) can be beneficial for: 

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1. Allowing people to feel more comfortable in the cold (i.e., cold adaptation)

2. Triggering further and more sustained increases in metabolism

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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.

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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). 

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DAY OR NIGHT?

After cold exposure, your body heats up—yes, HEATS up. 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.

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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.