It wasn’t just Gen Z and young millennials sneaking out of work and secretly taking time off over the summer months. Bosses have been at it too.

New research suggests that productivity does dip during the peak summer months, as workers across the office hierarchy leave their desks to enjoy the warm weather. That makes the seasonal slowdown more than just a meme about “summer Fridays”: for managers, it can show up as missed output, thinner coverage, and more pressure on teams that stay behind.

The software company PDFFly surveyed 2,000 managers and senior managers and found that while 85% of managers suspect employees are making up excuses to get extra time off in the summer, half of managers say they are doing the same thing themselves.

The excuses are strikingly similar whether the person is an entry-level worker or a boss.

Managers said they believe employees are pretending their Wi-Fi is down, inventing dental or doctor’s appointments, or calling in sick to take additional time off.

But when asked about the excuses they use to step away from work and enjoy a day in the sun, managers admitted they rely on fake sick days, followed by exaggerated family obligations, fake appointments, or made-up technical problems. Nearly 10% said they are not even making excuses, instead logging on and doing no work.

The impact on business appears to be real. Six in 10 managers said output falls in summer, with 18% describing the drop as “significant,” 42% calling it “slight,” and 37% saying they see more than a 10% decline in productivity. A third said the problem has become severe enough that the company lost a client or missed a deal.

Nearly 4 in 10 millennials say they take “quiet vacations”

Managers are not the only ones finding creative ways to take more time off.

Nearly 4 in 10 millennials say they have taken “quiet vacations,” secretly going on holiday without telling their boss. They bring their work phone with them to the beach and check in occasionally to avoid being caught. A separate study from Resume Builder found that 43% of quiet vacationers slip away for up to three days at a time, while a quarter take the entire week off.

Others have gone further and used medical leave to take up to 12 weeks off, with the time job-protected and, in some cases, paid.

Some people have described using the system for extra PTO, while others say the time off has been necessary. One TikToker said using the leave to focus on her mental health, without the risk of being fired, was “life-saving.”

Researchers behind the quiet vacationing study said the trend is driven not by laziness but by anxiety. Two in five workers said they are afraid that asking for time off will hurt their standing at work.

In both cases — medical leave and secret vacations — the common thread is not that the work is too easy. It is that some workers do not feel safe asking for a break honestly, even as employers are left to manage the fallout of reduced visibility and interrupted workflows during the busiest vacation months.

This story was originally featured on Fortune.com.