Americans have strange work habits.
The phenomenon of finish dinner, play with the kids, then log back seems to have permanently invaded U.S. homes, with roughly one in four putting in at least a few hours between 10 p.m. and 6 a.m. on a regular basis, according to a recent report by the National Bureau of Economic Research.
Though workers and experts are often split on whether burning the midnight oil is good or bad for an employee's mental and physical health, Russell Wayne Clayton, a professor of management at Saint Leo University, said the diagnosis depends on one simple issue: Who's in control.
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"Individuals who have the choice as to whether or not they want to check email at midnight ... may have their work-life balance less impacted, if impacted at all, by the act of the midnight email logon," he said. "In fact, someone like that may actually choose to check email at midnight because they can do so and because they might be more productive then."
Adam Berliant, who works at Microsoft's headquarters near Seattle, said he finds it "less stressful" to deal with things as he thinks of them, instead of waiting until he gets to the office. Mimi Antonetti, a caterer who lives near Pittsburgh, shared his sentiment.
"Whenever I did send an email after midnight it was usually because I was afraid I would forget what was on my mind at that point," she said.
Some workers can also use late-night logons as a tradeoff with their employers, Clayton said. For example, someone might get permission to leave the office at 4:15 p.m. to pick up their kids, in exchange for the expectation they will finish up a project from home later that night.
"In my case, I check email late, after my daughter has gone to bed," Clayton said. "This allows me to play with her before her bedtime and is a strategic choice on my part."
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Geography, or course, also plays a role, with many workers communicating through the night with overseas clients.
Although plenty of night owls think they're more productive after others have turned in for the day, late-night work can carry perils. Studies show people with late-shift sleep schedules are more prone to depression, and some claim those who regularly stay up past midnight suffer something akin to chronic jet lag.
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Looking at email right before bed can also make it harder to fall asleep. Scientists believe the glow from electronics confuses the brain about nighttime, delaying the release of sleep-inducing hormones. What's more, few people can sleep easily just moments after wrapping their heads around work problems.
"Evening types experience anxiety and negative mood, tend to have lower self-esteem, perform worse in school and may be more susceptible to stress," according to a study by the National Institutes of Health.
—By Bob Sullivan, special to CNBC.com