Could it be? Are Americans finally starting to use their vacation days?

For the past 15 years, US workers have wasted millions of vacation days, opting to go into the office rather than relaxing and using their allotted time off.

But a pair of studies released within a day of each other found that the pendulum could be swinging in the other direction. It’s a painfully slow swing, but even the tiny shift could mean that the beleaguered masses toiling with dark circles under their eyes are finally beginning to see the light, and not just the light from their laptop screens.

In 2016, the average US employee took 16.8 days of vacation. That’s up from 2015’s 16.2 days per year, according to Project: Time Off, a travel-industry-funded initiative. The percentage represents only an additional half day, but it’s a rare rise. From 1978 to 2000, the average worker took 20.3 days off.

“For the first time in many years, there is reason to believe that America’s bad vacation habits may be improving,’’ Project: Time Off senior director and report author Katie Denis said.

Even with the increase, US workers still left 662 million vacation days unused and withering on the vine.

Another study, from the job site Glassdoor, found that 91 percent of US workers took at least some time off in the last 12 months, up from 85 percent in 2014.

But all of these findings are filled with caveats and asterisks. The Glassdoor study found that although employees are taking more time off, they’re unplugging from the office less. Nearly 30 percent of workers who took time off in the past year report being contacted by a co-worker while out of the office. Those employees said they also had a difficult time not thinking about work while they were away from the office, and some were contacted by their bosses.

The Project: Time Off study found that millennials are even less likely to take vacation time, hoping to be viewed by their bosses as “work martyrs,’’ a term used frequently in the study.

In a third study — because there’s always room for more unsettling news about bad vacation habits — the travel industry website Skift asked the question, “Have you already planned and booked your summer vacation?’’

The answers weren’t encouraging.

Nearly 42 percent said they were not taking any time off this summer, while another 35 percent said they hadn’t booked yet.

“Many travelers are saying that they’re hunkering down for another summer of little or no time away from the office,’’ said Dan Peltier, a reporter at Skift.

So perhaps the light at the end of the vacation tunnel might be from a computer screen rather than the sun after all.

Christopher Muther can be reached at muther@globe.com. Follow him on Twitter @Chris_Muther.