Checking Work Email at Night? Here's Why You Should Stop

Using a smartphone to get more work done at night makes employees less productive the next day, new research suggests. Workers who monitored their smartphones for business purposes after 9 p.m. were more tired and less engaged the following day on the job, researchers found.

Russell Johnson, a Michigan State University assistant professor of management and co-author of the study, said many smartphone owners consider the devices to be among the most important tools ever invented when it comes to increasing productivity of knowledge-based work. Yet, the National Sleep Foundation says only 40 percent of Americans get enough sleep on most nights and a commonly cited reason is smartphone usage for work.

"Smartphones are almost perfectly designed to disrupt sleep," Johnson said. "Because they keep us mentally engaged late into the evening, they make it hard to detach from work so we can relax and fall asleep." [Job Search 2014: What's In, What's Out]

As part of their study, researchers conducted two experiments. The first had 82 upper-level managers complete multiple surveys every day for two weeks, while the second surveyed 161 employees daily in a variety of occupations, including nursing, manufacturing, accounting and dentistry.

Both studies' surveys showed that nighttime smartphone usage for business purposes cut into sleep and sapped workers' energy the next day in the office. The second study also compared smartphone usage to other electronic devices and found that smartphones had a larger negative effect than watching television and using laptop and tablet computers.

Researchers said that besides keeping people mentally engaged at night, smartphones emit "blue light" that seems to be the most disruptive of all colors of light because it hinders melatonin production, a chemical in the body that promotes sleep.

"So it can be a double-edged sword," Johnson said. "The nighttime use of smartphones appears to have both psychological and physiological effects on people’s ability to sleep and on sleep's essential recovery functions."

Johnson said one potential solution is turning off the smartphone at night, but he understands that isn't always practical in today's business world.

"There may be times in which putting off work until the next day would have disastrous consequences and using your smartphone is well worth the negative effects on less important tasks the next day," he said. "But on many other nights, more sleep may be your best bet."

The study will appear in the Organizational Behavior and Human Decision Processes journal. It was co-authored by two doctoral graduates from Michigan State's Broad College of Business: Klodiana Lanaj, an assistant professor at the University of Florida, and Christopher Barnes, an assistant professor at the University of Washington.

Originally published on BusinessNewsDaily.

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