Game of Thrones and The Walking Dead can be a lot of fun, but a new study shows that watching more than five hours of television a day can mean less testosterone and a lower fertility rate.
Researchers at Denmark’s Copenhagen University found that more than five hours of TV can cut a man’s sperm count by a third, making him less likely to become a father. Binge-watchers had average sperm counts of 37 million per milliliter of fluid, while men who hardly ever watched TV had a more healthy 52 million per milliliter, according to results published in the American Journal of Epidemiology. Sperm counts range from 40 million to 300 million per milliliter, and anything below 15 million is considered a low count.
Perhaps more terrifying, these TV addicts also had lower levels of testosterone, the male hormone which helps produce sperm, and is also responsible for other masculine qualities such as a deepening voice, beard growth, and muscle mass. The study involved 1,200 young men who signed up for military service between 2008 and 2012.
Television may not be the direct cause, however. As Pat Hagan with Britain’s The Daily Mail pointed out, those who watch too much TV are also less likely to exercise regularly or to eat a healthy diet. Indeed, a 2013 study in the U.S. found that 15 hours of exercise a week could increase sperm quality.
Over the past two decades, several studies have highlighted a general decline in men’s sperm count. Scientists have blamed everything from high-fat junk food diets to traces of a contraceptive pill in drinking water (scary), and even the chemical BPA used in some plastics. This latest study suggests the most important factors may be men’s laziness and a love of TV.
Most fascinatingly, sitting in front of a computer screen did not have the same negative effect on testosterone and sperm counts, the Danish scientists discovered. Perhaps this time, considered work, does not conflict with healthy eating or exercise in the same way that TV does.
“Time spent watching television, but not time sitting in front of a computer, was associated with lower sperm counts,” the researchers wrote. “Furthermore, decreases in testosterone were detected in men watching many hours of television.”
These findings follow another study, which suggested watching too much TV raises the risk of dying from a blood clot on the lungs. For every extra two hours of TV-watching per day, the risk of fatal pulmonary embolism increased by 40 percent, and watching five or more hours made people more than twice as likely to die as those watching less than 2.5 hours.
Again, these results do not demonstrate causation: watching television is not likely the thing that kills you. Instead, more hours of TV are likely correlated with an unhealthy lifestyle which can prove fatal. As Hagan pointed out, polls have suggested that nearly half of all adults in Britain admit to doing no cardio exercise at all with a further 25 percent confessing they merely did one hour a week or less.
If you want to live longer, it’s ok to watch TV — just make sure that’s not the only way you spend your free time. As much we love The Walking Dead and Game of Thrones, life is about more than seeing Rick Grimes kill zombies and figuring out who Jon Snow’s real mother is.