Stress vs Cold: An ice bath could save your life.

Updated: May 9

When psychologists study stress response, many of them use a protocol called the Socially Evaluated Cold Pressor Test (SECPT, Schwabe et al 2018). The test requires subjects to immerse one hand in freezing cold water for 3 minutes, while other people are watching.

Although it doesn't sound very stressful, the protocol elicits a strong response from the sympathetic nervous system (Schwabe et al. 2008) that governs involuntary physiological responses to fear and anxiety. For example, under the SECPT, subject's heart rate increases, blood pressure increases, cortisol and norepinephrine increase in ways that are characteristic of the fight or flight response to danger.

Although most people are familiar with ice baths for exercise recovery, what the SECPT demonstrates is that the physiological, psychological, and endocrine responses in the hypothalmus-pituitary-adrenal (HPA) axis are much more complex than the responses in the muscles. The fact that cold exposure relieves symptoms of multiple sclerosis suggests that there are also nervous system benefits.

Given these complexities, it is impossible for scientists to say how much of the body response to cold water immersion is due to psychological factors within our control, and how much is due to physiological factors already programmed into our biology. For example, in Raynaud's syndrome, patients experience an involuntary spasm of the smooth muscle tissue that surrounds blood vessels. This causes extreme vaso-constriction, shutting off blood flow to extremities like fingers and toes, as if the body were being exposed to cold temperatures, even when temperatures are mild. The specific cause of Raynaud's remains uncertain. What is clear is that the syndrome is a complex interaction of physiological and psychological responses to cold stress.

Either way, multiple studies of subjects who gain experience with the SECPT demonstrate that the physiological markers of cold stress evolve over repeated exposures. For example, Minkley et al. 2014 showed reduced heart rate response to SECPT in the third exposure, compared to the first. Both cortisol release and subjective stress perception were also reduced upon repeated exposure -- although blood pressure was not.

The Minkley study suggests that physiological and psychological responses to stress can be trained -- exactly the same conclusion of Scott Carney's best-selling book What Doesn't Kill Us, in which he describes the incredible control of autonomic nervous system, metabolic, and immune system responses exhibited by ice bath guru Wim Hof.

The world's foremost expert on the SECPT is Lars Schwabe, Professor of Cognitive Psychology at Ruhr University in Bochum, Germany. To discover more about stress response, he designed an experiment comparing two distinct processes that are known to influence behavior:

  • incentives, and

  • habits.

What he discovered is that habits are much better predictors of behavior under stress than incentives (Schwabe & Wolf, 2009).

That makes sense to Morozko.

Given what we've learned about human cognition and decision-making from Daniel Kahneman's Thinking Fast and Slow (2011), we know that goal-directed behavior guided by incentives requires a much greater cognitive load. That is, incentive-driven thinking is slow. But habits require so little thinking that habitual behavior happens fast.

Under stress, resources for slow thinking are scarce. Our cognitive processes can be overwhelmed by our body's physiological response to stress, interrupting the slow thinking necessary for incentive-driven behavior. That's when we must rely on our habits.

What this suggests is that the only way to improve our stress response, and maybe our performance under pressure, is to practice experiencing stress so that we can form better habits.

Because cold exposure is proven to induce stress, perhaps the ice bath is the perfect way to practice improved stress response habits.

At Morozko Forge, we've been gathering brain wave data on subjects plunging into whole body cold water immersion, to measure the response of their brain activity to the cold exposure. What we're beginning to discover is that the cold can have a calming effect on brain activity, and that this calming effect can be improved over time.

In fact, training yourself to overcome the stress response to cold exposure may save your life. In her 2013 TED talk 'How to make stress your friend', Stanford Psychologist Kelly McGonigal reports that it is not stress that kills you.

It is the story you tell yourself about that stress.

According to McGonigal, believing that stress is harmful could be the 15th greatest cause of premature death in the United States.

To retrain her subjects to improve their stress response, McGonigal administers a socially evaluated stress test in her laboratory. That is, she uses the social evaluation portion of the SECPT, but not the cold pressor portion. She concludes that subjects who were told that their stress responses are helpful experience more relaxed blood vessels, despite elevated heart rate. She says, "My goal as a health psychologist has changed. I no longer want to get rid of stress from your life. I want to make you better at stress."

Morozko wants that for you, too.


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