Postponed vacations, holidays in isolation and back-to-back virtual meetings are taking a toll on millions of American workers.

Why it matters: As we head into the fall, workers are feeling the burnout. Such a collective fraying of mental health at work could dampen productivity and hinder economic growth across the country.

• "If your team enters 2021 exhausted and end-of-rope from 2020, they won’t have the urgency, creativity and resilience you need to have a strong year," says Deidre Paknad, CEO and co-founder of the software company Workboard.

What's happening: The typical American worker has always underused vacation days. In 2019, U.S. workers earned 23.7 days of paid time off, but used only 17.2, per U.S. Travel Association data.

That trend appears to be even worse this year, as people delay taking time off either because they're waiting until they feel safe traveling and seeing friends and family or because they're worried about job security.

• 37% of surveyed workers are postponing PTO until they can safely travel, while 14% say they have too much work to log off, per a study conducted by the human resources consulting firm Robert Half; 22% say they would take a vacation but are trying to save money because of the pandemic's uncertainty.

On top of no vacations, workdays themselves can be more stressful during the pandemic.

• With every employee stationed in front of a computer, managers and colleagues can schedule hourlong meetings without any breaks in between.
• "What we heard most about burnout is that every single second is scheduled," Paknad tells Axios. "There's no time to think."
• To fix that problem, several companies — including Paknad's — are blocking off certain hours as meeting-free to give employees time to exercise or spend time with their kids or just catch up on their own work.

Companies are picking up on the burnout and begging employees to take a break.

• Nearly 40% of workers said their bosses have urged them to take time off, according to August survey data from Robert Half. That's up from 25% in May.
• "One of the simplest things for leaders to do is practice what you preach," Paknad says. "Take vacations."

What to watch: The most immediate economic effect of delayed vacations is already apparent in America's travel industry, which is set to lose around $500 billion this year and $1.3 trillion by 2023, says Tori Barnes of the U.S. Travel Association. There are also millions of hotel, airline and other jobs at stake.

• Sign of the times: Hilton is closing its 478-room Times Square behemoth for good on Thursday.