Cold · 11
2–3×
rise in the stress hormone noradrenaline after each dip
A short, very cold dip sends noradrenaline up two- to threefold.
Twenty seconds in 0–2°C water raised noradrenaline two- to threefold after every swim for 12 weeks.Source 1 · 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 ↗ The famous 250% dopamine figure came from blood drawn after an hour in 14°C water.Source 2 · 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 ↗
Try this
Use a plunge as a wake-up if you like it, and judge it by how you feel in the hour afterward.