Cold plunges, what we know and don't

A 2025 review pooled 11 randomized trials of cold water at 15°C or colder in healthy adults. Stress was lower 12 hours after a plunge, but not at other times. Inflammation markers rose for at least an hour afterwards, which is a normal stress response. Some studies found better sleep and quality of life. Mood didn't change. In one large trial, people who took cold showers had 29% fewer sick days off work.

An earlier review of 104 studies found signs that regular cold exposure may reduce body fat and improve insulin sensitivity. Most of those studies were small, often included only men or only women, and used different water temperatures, so the authors couldn't draw firm conclusions.

None of these studies tested whether cold plunges help you live longer. That's why Ageon tags them as emerging evidence and gives them 1 point. If you enjoy them, keep going. If you don't, sleep, strength and cardio are a better use of your time.

Sudden cold water makes you gasp and spikes your heart rate and blood pressure. That reaction causes drownings and can trigger heart problems. Talk to a doctor first if you have a heart condition. Start with short, mild exposures, never plunge alone, and get out if you feel numb.