What do 31 million employees have in common? They all participate in at least one (in many cases more than one) Fantasy Football league! For those of you who are unfamiliar with what has become a national obsession, Fantasy Football is an interactive online competition in which users compete against each other as general managers of virtual “fantasy” teams built from “drafting” real National Football League players. “Owners” are able to draft, trade, add/drop players, and change rosters every week.

Just like your employees’ devotion to filling out brackets each year when “March Madness” and the NCAA basketball tournament rolls around, Fantasy Football is a sports fan’s obsession. But unlike March Madness, which only requires an initial investment of time and a few days of non-stop basketball games, Fantasy Football lasts four MONTHS and requires its owners to check injury reports, keep up with statistics, and – in recent weeks – monitor arrest records and indictments (thank you, Ray Rice and Adrian Peterson).

Sounds pretty time-consuming, right? A recent study by Challenger, Gray & Christmas estimates that employers will suffer $13 billion in lost productivity due to employees’ participation in (obsession over?) Fantasy Football leagues. There was a time not so long ago when employers could control their employees’ Internet access and usage simply by placing a block on their access via desktop computer. That time is long past. Employees now have full access to the Internet through their smartphones and tablets, and the Fantasy Football “apps” have gotten better each season. (I’ve already dropped a QB and added a new WR while writing this article!)

This is not a new phenomenon. For years employees have been making travel plans, on-line shopping and paying personal bills through the Internet while on company time. I even know someone who met their spouse responding to on-line dating ads while at work. But when so many people engage in the same activity for so many hours over so long a time period, employers need to consider the impact.

But how accurate is this $13 billion number? Challenger’s estimate is actually a measure of wages paid to unproductive workers. For example, if a company is paying its employee $15 per hour, and one hour of his or her time is spent researching NFL players for Fantasy Football, then that is $15 in lost wages. Challenger calculated the total lost productivity amount using that basic formula and plugging in other numbers like the country’s average hourly earnings, total number of working age Americans who play Fantasy Football, and assuming that each participant conservatively spends just two hours per week managing their teams while on the job. Challenger admits it is a non-scientific study. But because it is such a massively popular distraction, employers must take notice.

So is Fantasy Football a bad thing for employers? Not really. It may have some overall, minor impact on workplace productivity, but historically there has been no measurable dip in GDP or productivity in the third or fourth quarters that is directly linked to Fantasy Football.

In fact, there are some positives that come from workplaces where Fantasy Football is part of the proverbial water cooler discussion. Many employers believe that Fantasy Football is a positive influence in the workplace because it increases staff morale and camaraderie among employees. For those employees who participate, it is also a great way to keep in close contact with their customers, clients, and business contacts who also participate in a Fantasy Football league.

Employers should be careful, however, that no employee feels excluded or discriminated against due to Fantasy Football being played in their workplace. Lawsuits have been filed in the past based on sex and religious discrimination stemming from exclusion from Fantasy Football leagues and other social events. Supervisors should be trained to watch for signs of discrimination in workplaces where Fantasy Football is played, and must take responsibility for their employees to ensure no one is excluded for an unlawful reason. And employees must take responsibility for themselves not to let owning their team interfere with their job duties in any way. Winning your Fantasy Football league is a great feeling – but not at the expense of losing your job!