Should you be taking some cold showers? Researchers had subjects add a cold shower at the end of their regular hot shower routine to measure its effects on heath and other lifestyle factors. They found that cold showering significantly reduced the number of sick days that the subjects took during the study (though not the number of illness days). The authors hypothesize that this was caused by the invigorating effect of the cold shower, which some subjects compared to a jolt of caffeine. In fact, the subjects enjoyed the cold showering so much that the majority of them continued to do it even after that phase of the study ended.