Research published in the journal PLOS One demonstrated that regular cold exposure through cold showers was associated with a 29% reduction in sickness absence from work. The study followed 3,018 participants and found that those taking cold showers reported fewer sick days.
Source: Buijze, G. A., Sierevelt, I. N., van der Heijden, B. C., Dijkgraaf, M. G., & Frings-Dresen, M. H. (2016). The Effect of Cold Showering on Health and Work: A Randomized Controlled Trial. PLOS One, 11(9), e0161749.
Studies in the Journal of Applied Physiology have shown that cold water immersion triggers a 2-3 fold increase in blood levels of norepinephrine, a hormone and neurotransmitter that functions as a natural mood elevator and anti-depressant. This explains the energising and mood-boosting effects of cold showers.
Source: Shevchuk, N. A. (2008). Adapted cold shower as a potential treatment for depression. Medical Hypotheses, 70(5), 995-1001.
Research from the New England Journal of Medicine shows that cold exposure activates brown adipose tissue (BAT), a metabolically active fat that burns energy rather than storing it. Regular cold exposure can increase BAT volume and activity, potentially aiding in weight management and metabolic health.
Source: van Marken Lichtenbelt, W. D., Vanhommerig, J. W., Smulders, N. M., Drossaerts, J. M., Kemerink, G. J., Bouvy, N. D., Schrauwen, P., & Teule, G. J. (2009). Cold-activated brown adipose tissue in healthy men. New England Journal of Medicine, 360(15), 1500-1508.
Studies in the field of psychophysiology have demonstrated that regular exposure to controlled stress like cold water increases the body's resilience to other forms of stress. This process, called hormesis, improves overall stress adaptation abilities and mental toughness.
Source: Hof, M., & Yon, E. (2017). The Way of the Iceman: How the Wim Hof Method Creates Radiant, Longterm Health.
Research published in the Journal of Physiology has shown that cold water exposure causes vasoconstriction followed by vasodilation upon warming, effectively training the circulatory system and improving overall circulation. This can lead to better nutrient and oxygen delivery throughout the body.
Source: Johnson, J. M., & Kellogg, D. L. (2010). Local thermal control of the human cutaneous circulation. Journal of Applied Physiology, 109(4), 1229-1238.