Perhaps it's the inexplicable craving for a day off ahead of the big Labour Day holiday. Perhaps it really is a stomach bug, or that more recent fiend — the coronavirus. And of course, it might just be the blues at the end of summer.

Whatever the reason, Aug. 24 is when American workers most often tell their bosses they simply cannot work that day.

The other day workers typically fail to show up? Feb. 13, usually around the Super Bowl and Valentine's Day. Tough to guess why.

These dates came from a study by Flamingo, a firm which helps companies manage employee absences and medical leaves, which analyzed data on sick days taken by American workers over the past five years.

Some 300 businesses with over 10,000 employees participated in the study which found an average 0.9% of those employees were out sick on Aug. 24, a higher percentage than on any other day of the year, according to David Hehenberger, Flamingo’s founder.

People cited stomach bugs more than half the time as the reason for calling in ill, with the majority of sick-day requests mentioning symptoms such as vomiting or diarrhea. These issues surpassed coronavirus, which accounted for about a quarter of total absences. Injuries like broken bones and muscles strains, which caused 6% of people to stay home from the office, were also cited.

Beyond physical ailments, Paaras Parker, chief human resources officer at payroll software company Paycor, said her organization observed a notable uptick in workers staying home with anxiety or stress-related conditions, which accounted for almost 9% of sick leaves in the Flamingo survey. “It's not necessarily that they have strep or a fever, but that they need a day for themselves,” she said.

With employee burnout reaching a post-pandemic high earlier this year, workers feeling emboldened to take mental-health sick days is a “welcome change” in workplace attitudes, Parker said.

The advent of remote work is also changing the culture around sick leave. A new survey by WFH Research shows that workers feeling ill but without an option to work remotely are nearly twice as likely to come to the office with symptoms as their hybrid counterparts.

That spells trouble on the health front as return-to-office mandates harden and office densities increase, contributing to a rise in breeding grounds for contagious illnesses such as influenza and the common cold. “People clearly feel more comfortable working from home when they're coughing or when their nose is very stuffy,” said Jeff Levin-Scherz, population health leader at insurance company WTW, formerly Willis Towers Watson. “If they feel well enough to work, they can feel more comfortable knowing they're not going to pass anything to anybody else.”

But for employees that are still tied to the office, he stresses the importance of continuing  good  hygiene such as hand-washing and insisting their companies consistently check air quality, practices that became routine during the pandemic.

“These days, where many knowledge workers just don't come to the office, some of these efforts to make healthier workplaces might actually be amenities that help encourage people to show up,” Levin-Scherz said. He adds that perks like access to healthy food and exercise facilities could serve a dual purpose of boosting employee health as well as office attendance.

In any event, it’s never a good practice to poke holes in an employees’ reason for claiming a sick day, Parker said. “I don't think it's our place to guess why somebody is taking time off, but to realize that human beings need time off and to create environments and policies that allow them to exercise this right when need be,” she said.