Cold-water immersion has surged in popularity, with ice baths and cold showers touted as shortcuts to better health. Advocates claim it improves mood, sharpens focus, and speeds up recovery. A recent study found that while cold exposure temporarily increased inflammation, it reduced stress 12 hours later, improved sleep, and reduced sick days.

Researchers conducted a systematic review and meta-analysis of 11 studies involving more than 3,100 healthy adults investigating the effects of cold-water exposure on mental and physical health markers, including mood, stress, immunity, inflammation, and sleep quality. Participants in the various studies took cold showers or ice baths at temperatures between 7°C (45°F) and 15°C (59°F) for at least 30 seconds.

The analysis revealed that inflammation spiked immediately after immersion and stayed elevated for an hour. Interestingly, stress levels dropped 12 hours later but remained unchanged at other time points. Cold exposure did not immediately boost immune function, but a separate analysis linked cold showers to a 29% drop in sickness absence. Participants reported better sleep and overall well-being but no changes in mood.

These findings suggest that cold-water immersion may offer short-term stress relief and potential immune benefits, with highly time-dependent effects. The effects of cold exposure may be due to hormesis—a compensatory defense response that conditions the body against future stressors. Learn more in Aliquot #97: Thermal Stress, Part II: Unveiling the Power of Cold Exposure on Health and Performance