If you are guilty of updating your fantasy football roster or checking scores at work you are not alone and you are costing employers billions.

Outplacement firm Challenger, Gray, and Christmas has released their report on the effects of the fantasy football season on productivity and what they have found is pretty eye opening.

They say that over the course of the NFL season, employers in the U.S. will lose over $13 billion in productivity.  It is the unintended consequence of the NFL's push to get fans more engaged.  Sportstalk 790 host Matt Thomas says the NFL wants people to play fantasy football, "It's what the NFL has built, they want you playing fantasy football because they want you to care about a game between the Patriots and the Dolphins.  That you would normally never care about because it's not your team."

Challenger, Gray, and Christmas also tell employers not to crack down on all the web-time looking at stats and figures.  They say you should create company fantasy football leagues to promote camaraderie and build morale.