Cold-Water Immersion and Brain Health

Cold-Water Immersion and Brain Health

“But, there is still every reason for healthy people to take cold showers, or swim outside in cold water. It gives you the feeling that you are alive.”
― Wim Hof

Why is cold exposure valuable?

Cold exposure is an obvious stress to the body, as it universally produces a shivering reaction in people.  It has even been theorized that a lack of certain physiologic stresses like cold water immersion causes abnormal brain function including mental illness.

Our ancescold watertors certainly were exposed regularly to uncomfortably cold environmental temperatures prior to the availability of suitable clothing and shelter.  This thermal stress has now been minimized in modern society, and individuals have rather small windows of comfort.

Cold-water immersion is consistently described as an invigorating experience that creates a sense of well-being, along with a sense of being present in the moment.  Even a single exposure to cold water can improve mood.

Cold exposure and mental health

Cold-water immersion has been repeatedly linked to improvements in mood and mental disorders.

There was a 24-year-old woman who suffered from depression and anxiety despite being on medication since the age of 17 who took up cold-water swimming on a weekly basis.  Within a month, she was able to reduce her medication and in 4 months was able to stop her medication entirely.

How is cold exposure beneficial?

There are several reasons why cold showers are thought to be beneficial in depression.

  • The thermal conductivity of water is approximately 30 times that of air.
    On the surface of the skin, there are 3-10 times more receptors for cold as there are for heat.  Immersion of the body in cold water sends a tremendous amount of electrical impulses from the periphery to the brain.  In fact, cold water exposure is theorized to have a beneficial antipsychotic effect similar to Electroconvulsive Therapy (ECT) as a mild shock to the sensory cortex.  This flood of sensory input from a stressful stimulus causes decreased pain sensation and is thought to suppress transmission of abnormal brain signals such as those seen in psychosis.
  • In human subjects, immersion in 57 deg F water increased norepinephrine by 530% and dopamine by 250%. These hormonal changes likely explain the euphoric feelings associated with cold water immersion.  Norepinephrine is both a neurotransmitter and a hormone.  It is also known as noradrenaline and is involved in our “fight or flight” response – it’s hormonal role.  It works as a neurotransmitter in the brain and spinal cord to increase alertness, arousal, and attention.  Norepinephrine also appears to have anti-inflammatory effects.

  • Cold exposure increases brown adipose tissue – fat tissue that is rich in mitochondria and is metabolically active, capable of producing heat. This metabolically active type of fat appears to improve whole-body metabolism.  The variability of brown fat content likely explains why some individuals are remarkably resilient to cold temperatures, e.g. wearing shorts and short sleeves when others are bundled up in winter clothing.
  • Cold exposure increases beta-endorphin, known to produce a sense of well-being.
  • Cold exposure activates the sympathetic nervous system – the fight or flight response, preparing the body to take action.
  • Cold exposure is a physiologic stress that likely has a hormetic effect by forcing the body to recover from a cold stress to restore normal body temperature.


Safety concerns

Brief exposure to cold water appears to be safe, with negligible effects on core body temperature.  Individuals with severe or unstable cardiovascular disease should avoid sudden cold-water immersion.


Cold-water immersion appears beneficial to brain health and overall metabolic health, through some similar mechanisms as temperatures on the other extreme.

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