“Even if you take a sick day, you're still emailing in the morning, checking in later in the day,” Kit Warchol, head of content marketing for Skillcrush, an online coding school, tells the New York Times. “It's become more of a norm to write to your colleagues and tell them you're working from home.”

Of course, there are still plenty of jobs where on-site work is required. In those jobs, taking a sick day means not working at all. That includes food service workers, many of whom do not benefit from paid sick leave. They therefore have a strong incentive to work sick, putting coworkers and customers at risk of getting sick.

While employers have long strategized on how to reduce sick leave abuse, some employment experts believe that presenteeism is a much bigger problem. Presenteeism often refers to employees working despite an illness, but a broader definition includes employees who are at work but constrained by a lack of motivation.

In 2016, GCC Insights conducted a survey of 2,000 employees on their work habits. Based on their responses, GCC estimated that employees spent an average of 57 days a year on the clock doing something besides work.

One of the ways employers may seek to reduce burnout and therefore reduce presenteeism is by encouraging employees to take time off, both for vacation and for illness. Even if an employee is able to send emails and analyze spreadsheets, it may work out better in the long-run if they took the whole day to rest.

Read more:

• Paid sick leave: A legislative update
• Technology, work/life balance top factors in employee happiness
• Few employees 'unplugging' on vacation