Cold Plunge:
The Complete Guide

Cold plunge — also called cold water immersion (CWI) — means submerging your body in water typically between 39–59°F (4–15°C) for a short, controlled period. It ranges from a $20 bag of ice in a bathtub to an $8,000 chiller-equipped tub that holds temperature to the degree.

The core physiological trigger is a shock to your sympathetic nervous system. Within seconds of immersion, your body releases a surge of norepinephrine — a hormone and neurotransmitter linked to alertness, mood, and focus. Regular cold exposure has also been shown to blunt inflammation markers and reduce perceived muscle soreness after intense training.

There's a third effect people chase just as often: dopamine. Research from the Huberman Lab and others shows cold immersion can raise circulating dopamine by 150–250% for hours afterward — which is part of why so many people describe cold plunging as addictive in the best way. None of this requires extreme cold: most protocols call for 50–59°F for 2–5 minutes, a few times per week.