No matter the industry or whether you're a salaried or hourly worker, employees in the U.S. can't seem to leave when their shift ends.

On average, American workers stay late 2.5 days a week, meaning most go home when scheduled only about half the time. And each after-hours session eats up 32 minutes of our free time, on average, according to a new survey of 1,188 working-age people by Amerisleep, a mattress company.

How you're compensated for your time makes no real difference to how often you stay late either, the survey found. While it might seem safe to assume salaried workers are more likely to keep at it after business hours end, it turns out hourly workers stay late an equal amount of days.

Where the two groups differ is in how long those extra work sessions last. Salaried employees spent an additional seven minutes, on average, working past their shift end, than hourly employees did when they decide to work late.

But both groups agree they stay late too frequently, saying a once weekly occurrence is acceptable.

So why are we putting in all these extra hours? For some workers, it was about impressing a boss or coworker, others said they couldn't get everything done during their typical shift, but 82 percent said they were directed or felt pressure from a supervisor to work later.

About 60 percent of workers believed their position was in jeopardy if they didn't comply with a boss's request, while 39 percent felt safe declining such an ask.

Financial gain is another key motivator: Workers who put in more overtime earn more money.

As one might expect, hourly workers who always took on additional shift time outearned workers who rarely stayed late to the tune of more than $14,000, on average, annually, according to the survey.

But salaried employees, who were also more willing to work late, pocketed more too — about $9,600 extra a year over coworkers who left on time, the survey found. One potential reason for this: They were seen as more dedicated and thus awarded higher raises or compensated with additional overtime wages.

Every additional dollar earned comes at a cost, though.

Workers who put in extra hours lost precious family time; 60 percent admitted to sacrificing moments with a partner or kids to work late. And 56 percent broke a promise to a partner or friend so they could keep on at the office.

Finally, extra work hours damaged people's health. People slept 46 minutes fewer on days they stayed late and had lower quality sleep on those days too. About half of workers ate more fast food when working late and 43 percent skipped the gym or other exercise they'd normally do.

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