Science Behind Cold Water Immersion

The mental and physical health benefits of cold water immersion (CWI).

Inflammation & immune response: CWI has been shown to reduce inflammation in the body. Many diseases, such as autoimmune diseases, are related to excessive or persistent inflammation. Examples include arthritis, Crohn's disease, asthma, depression, bipolar, cancer, and more. The immune system is connected to the sympathetic nervous system (the bodies ‘flight or fight’ response). CWI activates the sympathetic nervous system. This causes a release in epinephrine (adrenaline), which helps regulate the immune system function while suppressing our innate immune response of inflammation. CWI has been shown to decrease inflammation and improve inflammatory related diseases. It also increases levels of antioxidants which improve stress, mood, energy levels, focus and more.

For a more detailed explanation of the link between the CWI and the immune system, I recommend this study. https://link.springer.com/article/10.1007/s00281-020-00829-6

Mental health: CWI has been shown to improve mental health conditions such as depression and anxiety. These conditions are related to the sympathetic nervous system. CWI activates the sympathetic nervous system and increases the blood level of beta-endorphin (which blocks pain) and noradrenaline (which plays a role in your body's fight or flight response).
The body has a hypothalamic-pituitary-adrenal axis, or HPA axis. The HPA axis plays an important role in the body's response to stress through the interaction of several glands in the body. Dysregulation of the HPA is shown to be common in people with mental health conditions such as depression. For example, the endogenous opioid system which affects mood is deregulated in people with anxiety in depression. Studies have shown that CWI can influence these systems and help regulate them by activating the sympathetic nervous system. CWI has been shown to improve anxiety and depression. Also, the large amount of electrical impulses that CWI sends from the peripheral nerve system to the brain is also said to contribute to the anti-depressive effect.

Vascular health: CWI has been shown to improve vascular and cardiovascular health. The vascular system is composed of tiny muscles in our veins that open and close in response to the weather. Over time we have desensitised this system by wearing clothes and living indoors, causing these muscles to weaken. As a result, more stress is put onto the heart to pump blood, causing an increase in heart rate and cardiovascular disease. CWI has been shown to improve our vascular health by stimulating these muscles which causes them to strengthen. This puts less strain on the heart, reducing heart rate and cardiovascular disease. It also allows us to regulate our body temperature by improving blood flow, which has its own benefits such as improved energy levels.

Pain relief & mindfulness: CWI increases the blood level of beta-endorphin, which blocks pain and creates an analgesic effect (pain relief). CWI releases natural opioids and cannabinoids, which is why cold swims give a feeling of euphoria. CWI can also put us into deeper states of mindfulness by increasing blood flow to the limbic system of the brain.

References: Here are some of the references to scientific studies I have explored. There are much more out there, but overall there is a general cry from scientists for more research to be done on this topic, as many of these studies have limits with size and resources. My contention for providing this information is not to suggest each individual performs CWI for their health - this depends on the individual and their health conditions, and they should seek their own information or consultation before performing CWI. I am just providing information that supports my own personal experiences with CWI, which includes massive improvements to my depression, anxiety and chronic fatigue syndrome whilst highlighting the lack of relevant information available.

Improved muscle recovery & athletic performance

https://journals.lww.com/nsca-jscr/Fulltext/2017/05000/Effects_of_Cold_Water_Immersion_and_Contrast_Water.32.aspx

https://europepmc.org/article/med/24240118

Reduced pain

https://journals.sagepub.com/doi/abs/10.1177/10998004211063547

https://www.sciencedirect.com/science/article/abs/pii/S030698770700566X

Improvements in inflammatory diseases

https://journals.sagepub.com/doi/abs/10.1177/10998004211063547

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0225749
https://link.springer.com/article/10.1007/s10067-015-3009-8

https://www.mdpi.com/2218-1989/10/4/148/htm

https://www.wimhofmethod.com/cache/uploads/kcfinder/files/PNAS.pdf

https://pubmed.ncbi.nlm.nih.gov/6458557/