“A cold plunge raises your dopamine by 250%.”

The research found this

The number traces to a 2000 study from a lab in Prague. Ten young men sat in water up to the neck for an hour at a time at three temperatures, and the researchers compared them with a control condition in room air.1Source 1 · Clinical trialHuman physiological responses to immersion into water of different temperaturesŠrámek P, Šimečková M, Janský L, et al.. European Journal of Applied Physiology, 2000.Read the paper ↗PubMed ↗ After an hour at 14°C, plasma dopamine had risen 250% and plasma noradrenaline 530%. Adrenaline didn't change.

The same lab had run the same hour at 14°C four years earlier with young male athletes. That time plasma noradrenaline rose about fourfold, and neither adrenaline nor dopamine rose significantly.2Source 2 · Clinical trialChange in sympathetic activity, cardiovascular functions and plasma hormone concentrations due to cold water immersion in menJanský L, Šrámek P, Šavlíková J, et al.. European Journal of Applied Physiology and Occupational Physiology, 1996.Read the paper ↗PubMed ↗ Six weeks of repeated immersions in that study didn't clearly change the hormone response.

Dopamine in the blood and dopamine in the brain are separate pools. Sympathetic nerves release dopamine into the blood along with noradrenaline, and an NIH team estimated that 50–90% of plasma dopamine comes from them.3Source 3 · Clinical trialNeuronal Source of Plasma DopamineGoldstein DS, Holmes C. Clinical Chemistry, 2008.Read the paper ↗PubMed ↗ The gut adds a sulfated form of dopamine that a single meal raised more than 50-fold in one study.4Source 4 · Clinical trialSources and Physiological Significance of Plasma Dopamine SulfateGoldstein DS, Swoboda KJ, Miles JM, et al.. The Journal of Clinical Endocrinology & Metabolism, 1999.Read the paper ↗PubMed ↗ A 2026 review of catecholamine metabolism states that circulating catecholamines have extremely limited access to most brain tissue.5Source 5 · ReviewCatecholamine metabolism revisited: from neurochemistry to integrative physiology and pathophysiologyGoldstein DS, Eisenhofer G. Physiological Reviews, 2026.Read the paper ↗PubMed ↗

Short plunges have been measured for noradrenaline. When 12 adults spent 5 minutes in 8–12°C water up to the armpits, their plasma noradrenaline five minutes later was up 127% after a morning bath and 144% after an evening one.6Source 6 · Crossover trialEffects of time-of-day on the noradrenaline, adrenaline, cortisol and blood lipidome response to an ice bathBraunsperger A, Bauer M, Brahim CB, et al.. Scientific Reports, 2025.Read the paper ↗PubMed ↗ That study didn't measure dopamine. In ten Finnish women, 20-second dips in 0–2°C water raised noradrenaline 2–3-fold each time it was measured over 12 weeks, and among winter swimmers the rise after a test dip shrank after three months of regular swimming.7Source 7 · Clinical trialEffects of long‐term whole‐body cold exposures on plasma concentrations of ACTH, beta‐endorphin, cortisol, catecholamines and cytokines in healthy femalesLeppäluoto J, Westerlund T, Huttunen P, et al.. Scandinavian Journal of Clinical and Laboratory Investigation, 2008.Read the paper ↗PubMed ↗8Source 8 · Cohort studyEffect of Regular Winter Swimming on the Activity of the Sympathoadrenal System Before and After a Single Cold Water ImmersionHuttunen P, Rintamäki H, Hirvonen J. International Journal of Circumpolar Health, 2001.Read the paper ↗PubMed ↗