Topline results from the 2018 report include:

• 58 percent of workers globally describe themselves as very or somewhat vacation deprived, an increase from 53 percent in 2017 and 49 percent in 2016

• Gen Z and millennials (18-34) receive two less days on average (12) than any other age group in the U.S. and feel the most deprived (68%)

• Finances are increasingly a factor for Americans who haven't taken a vacation in the last six months, with more than half feeling like they can't afford a trip (54%, up 11% from 2017) – more than any other country surveyed except South Korea

• Americans use an average of two of their allotted vacation days per year for "life admin" (i.e. running errands, appointments)

Expedia's® 2018 report uncovers new attitudes and behaviors driving vacation deprivation and digs deeper into the positive effects of taking time off on mental health and self-image.

"One of the leading reasons people don't use their vacation days is that they're saving them for a big trip, which means they're going longer and longer between vacations," says Nisreene Atassi, global head of communications for Brand Expedia. "Bigger trips are great, but even a quick break can significantly improve quality of life. Aim to schedule a staycation or add an extra day onto a holiday weekend in between longer trips to get the best of both worlds."

"Fear of Switching Off" – is it all in our heads?

63 percent of Americans go six months or longer without a vacation, with more than a quarter (28%) going a year or more sans time off. Considering time off is so precious, one might be surprised to hear that a quarter of Americans admit to checking work email/voicemail at least once a day while on vacation.

While this behavior has stayed mostly consistent over the past decade, perhaps there's hope for future generations – younger workers are the least likely to check in frequently, at 19 percent for 18-34-year-olds, compared to 31 percent of the 50 and over crowd.

Interestingly, the pressure to be available may be self-imposed – only a small number of respondents say their managers (17%), junior staff (10%) and clients (12%) expect them to check-in daily while on vacation, proving most people need to simply give themselves permission to unplug.

Even a short getaway boosts self-esteem and confidence

With the biggest barriers to vacation being financial (54%), the desire to bank vacation days (23%) and inability to get time off work (17%), it begs the question: how long does one need to get away to reap the benefits of vacation? The study uncovered good news for those scarce on funds or time:

• Whether a long vacation (week or more) or a short one (2-3 days), post-trip people liked themselves more, felt more confidence in their ability to solve problems and felt more hopeful and outgoing.

• Longer vacations seem to yield slightly better outcomes, with each positive result seeing a roughly 10 percent boost compared to the 2-3-day trip.

Americans are savvy to this shortcut: 59 percent say they use short trips to fight off vacation deprivation in between longer getaways. To get the most out of a quick trip, try to keep travel time under four hours and choose accommodations close to the area's main attractions.

Taking a mental break

The growing focus and conversation around mental health may be changing how Americans vacation. A whopping 81 percent of U.S. respondents say they regularly take vacations where their primary goal is "mental wellness," and they overwhelmingly feel that vacation is a chance to "hit the reset button" on stress and anxiety (91%). Americans also report taking an average of two mental health days each year, which most feel should be considered sick days (67%), rather than vacation time.

"A wellness-centric trip doesn't have to mean a spa or yoga retreat, although those are popular options," says Atassi. "For most of us, recharging simply means we need to disconnect and slow down. Whether it's a family vacation or a solo escape, set rules about how often you're allowed to check email and try not to overschedule your days."