The Health Benefits of Cold Exposure (Physiology)
Physiology is the study of the internal mechanisms within living organisms. This includes DNA, molecules, cells, tissues, organs and whole body systems and the interactions/processes of all these parts which carry out essential functions for life. This article covers the effects that exposing the Human body to the cold has on our physiology and why exposing yourself to the element of cold may be something you consider incorporating into your life. I have another article which covers the Psychological rationale for cold exposure which is linked here.
So Norepinephrine is both a neurotransmitter and a hormone used by the brain and throughout the body. When the body is exposed to cold temperatures the release of Norepinephrine Is increased which causes a vasoconstriction throughout the body in order to conserve heat. However, as well as protecting the body from the cold, Norepinephrine positively affects focus, attention, anxiety, depression and general mood state. So much so, Norepinephrine is pharmacologically targeted when treating depression.
Serotonin and Norepinephrine reuptake inhibitors (commonly known as SNRI’s) are frequently prescribed antidepressants in the United Kingdom. SNRIs work by preventing the reuptake of Norepinephrine by the brain, allowing increased levels to be present in the brain. Interestingly, research has shown that subjects who were submerged in cold water of 4.4 Degrees Celsius for just 20 seconds displayed increased levels of Norepinephrine by 200 to 300 percent (Johnson et al., 1977). Considering the effects Norepinephrine can have on the metal state, I would consider this rise in Norepinephrine a valuable asset of cold exposure. The rise of Norepinephrine may only be temporary but it can allow for the experience of a different state of mind which can potentially be drawn upon post cold exposure. To be clear, I'm not stating that this evidence alone provides a case for treating depression. However, the practice of cold water exposure may be something people consider before going down conventional treatment routes such as medication which can be associated with magnitude of side effects (NHS, 2021).
Another Physiological response from the body to cold water is an increased production of the cold shock protein known as RNA-binding motif 3 (RBM3). In a study with Mice that were genetically modified to have Alzheimer’s, it was shown that exposing these mice to cold temperatures raised the presence of this cold shock protein. Interestingly, the heightened levels of this protein (induced through cooling) was shown to delay the onset of Alzheimer's disease highlighting the potential neuro-protective characteristics of the RBM3 protein. Evidence from the study showed that the RBM3 protein was responsible for synapse regeneration, preventing neuronal loss and prolonging the survival of the mice (Peretti et al., 2015).
A study by Giovanna Malluci from Cambridge University tested for the presence of this RMB3 protein in Humans. The study on cold water swimmers found that Humans do in fact possess this very same protein that was found in the mice and that it is markedly elevated when exposed to cold temperatures (Mallucci, 2020). Research is still ongoing into the full effectiveness the RBM3 protein can have on mitigating against diseases such as Alzheimers but the initial findings appear to be promising. Exposing yourself to cold temperatures may be something you consider to potentially protect yourself from the onset of neurodegenerative diseases.
I must note here the potential dangers of cold shock. If people are exposed to sudden drops in temperatures below 15 Degrees people can experience "‘cold shock’ which can lead to uncontrollable breathing, loss of consciousness and heart attacks. This is a serious risk factor to consider especially for those new to cold exposure . However, as many people show (including elderly wild/open water swimmers) we can acclimatize to the cold over time and have no problems. For more information on how to safely acclimatise to the cold please readthis article by The Outdoor Swimming Society. The Physiological and Psychological responses/adaptations by the body to the cold far outweigh the potential dangers/fears if done in a safe manner in which we give the cold the respect it deserves.
Reference list
Johnson, D. G., Hayward, J. S., Jacobs, T. P., Collis, M. L., Eckerson, J. D., & Williams, R. H. (1977). Plasma norepinephrine responses of man in cold water. Journal of Applied Physiology, 43(2), 216-220.
https://www.nhs.uk/mental-health/talk... (Side effects - Antidepressants)
https://www.outdoorswimmingsociety.com/how-to-acclimatise-to-cold-water/ Acclimatising to the cold
Peretti, D., Bastide, A., Radford, H., Verity, N., Molloy, C., Martin, M. G., ... & Mallucci, G. R. (2015). RBM3 mediates structural plasticity and protective effects of cooling in neurodegeneration. Nature, 518(7538), 236-239.
https://www.youtube.com/watch?v=n0-OCVPP6EE Mechanisms to Medicines in Neurodegeneration │ Prof. Giovanna Mallucci
