For those seeking luxury and romance, there are two tried-and-true ways to warm up on a cold winter's night: by a fireside or in a hot tub. Sadly, a Japanese study now shrinks that list by one. The team found that the mixture of a hot bath and a cold day could prove deadly: The rate of cardiac arrests that occur while bathing rises tenfold over the rate during summer. The team reviewed data from some 11,000 cardiac arrests that occurred between 2005 and 2007 in Japan, an appropriate location because "most people take a deep, hot bath, since traditional Japanese homes are not well-insulated as in the west and central heating is quite uncommon."
Before the cardiac arrest, 9% of people had been bathing, and the risk was linked to the temperature outdoors, with more arrests occurring on colder days. While the overall rate was still low—54 people per 10 million people per hour of bathing—it was still ahead of exercise, which had a rate of 10 people per 10 million per hour. The link is still a fuzzy one, notes Reuters, which adds that jumping into a hot tub on a frigid day can rapidly cause blood pressure to plummet, stressing the heart. "Preventive approaches such as warming a bathroom and hallway or refraining from taking a deep, hot bath could be important for high risk people," wrote the researchers. (Read more cardiac arrest stories.)