There's a reason why your office looks a little empty today. The Monday after the Super Bowl is one of the largest sick days of the year.

An estimated 13.9 million Americans plan to skip work today, according to a recent survey conducted by the Workforce Institute at Kronos Incorporated and Mucinex, a maker of cold medicine.

"We've been researching the big game's effect on the workforce for more than a decade, and while numbers may fluctuate each year, one clear fact remains: #SuperSickMonday is often the biggest day in America for calling out of work," Joyce Maroney, executive director of the Workforce Institute, said in the survey

This isn't a new phenomenon. Last year, 16.5 million Americans said they were going to call out after the Super Bowl, according to a study from the same two companies. While the numbers may fluctuate year-to-year depending on the flu season, the trend hasn't dissipated.

That's why 25 percent of the survey's respondents said they wished the day after the Super Bowl was considered a holiday. They aren't alone; 72 percent of human resources managers agreed people should have that day off.

If you're thinking of calling out today, find a different reason than a "fever" (unless you actually have one). That's the excuse that about 26 percent of people have used in the past. Another 14 percent said they had sore throat and 12 percent attributed their sick day to a headache.