In 2010, a team led by Alpa Patel of the American Cancer Society in Atlanta analyzed the data from a 14-year study of 123,000 middle-aged adults. When they compared mortality rates of those who spent six hours a day or more sitting and those who reported three or fewer hours — and when they took into account other factors such as diet — they found something surprising: Extra time on the couch was associated with a 34 percent higher mortality rate for women and 17 percent higher for men in the 14 years after they joined the study. It is not clear why there is such a big sex difference.
In another study, a team at the University of Queensland in Australia analyzed data on the television viewing habits of 8,800 Australians. They calculated that each hour of television correlated with 22 minutes off the average life expectancy of an adult older than 25. In other words, people who watch six hours of television a day face the prospect of dying, on average, about five years younger than those who don’t watch any.
