The things I saw beggar description. The visual evidence and the verbal testimony of starvation, cruelty and bestiality were so overpowering as to leave me a bit sick."
Gen. Dwight D. Eisenhower to Gen. George C. Marshall
April 15, 1945
describing visit to a German concentration camp
It works
Immediate brain effects
Short cold-water immersions trigger a surge in key neurotransmitters involved in attention, mood, and stress regulation.[pmc.ncbi.nlm.nih]
• Whole‑body cold immersion increases serotonin, dopamine, norepinephrine, cortisol, and β‑endorphin, which are central to emotion regulation, stress response, and reward processing.[pmc.ncbi.nlm.nih]
• After a single cold‑water bath, participants report feeling more active, alert, attentive, proud, and inspired, and less distressed and nervous.[pmc.ncbi.nlm.nih]
Cold exposure also changes large‑scale brain network connectivity in ways that may relate to antidepressant effects.[pmc.ncbi.nlm.nih]
• fMRI work shows increased coupling between medial prefrontal cortex and anterior insula/dorsolateral prefrontal cortex, and decreased coupling between medial prefrontal cortex and anterior cingulate cortex after cold immersion, patterns linked to better emotion regulation and reduced depressive rumination.[psychiatrypodcast +1]
• These connectivity shifts track with increased positive affect rather than just reduced negative affect, suggesting enhanced cognitive flexibility and self‑regulation.[pmc.ncbi.nlm.nih]