The findings should give employers pause about just how much they can fairly expect in terms of "emotional labor" -- the requirement to display certain emotions or feelings toward customers, clients and others at work.
"[Employees] could smile because they genuinely like their customers or they are simply happy, and in that case they are not engaging in what we call 'emotional labor' because they are not faking," explained lead researcher David Wagner, Ph.D. of Singapore Management University, in an email to the Huffington Post. "When they put on that happy face but don’t really feel it -- that’s when we start to have problems."
Researchers observed 78 bus drivers who worked for one transit company in the northwestern United States. Over two weeks, the study participants answered surveys before work, after their shifts and just before they went to bed at night. They were asked about hours of sleep, their moods during and after work, and whether or not they had put on a "performance" or a "mask" that day.
Wagner found that when a bus driver wore a fake smile, he or she was more likely to suffer insomnia that night than someone who wasn't faking it. Emotional acting was also linked to reports of feeling anxious or distressed, and also increased the likelihood of feeling emotionally exhausted at the end of the day. These people even reported more family conflict at home.
Meanwhile, people who reported behaving authentically -- either by not faking smiles at all or by smiling because they genuinely felt happy -- had much better sleep quality those nights.
Doug Pugh, Ph.D., chair of the Department of Management at Virginia Commonwealth University, wasn't involved in the research, but his past research on emotional labor does appear in Wagner's study. He praised Wagner for strengthening the study's results by taking workers' overall emotional stability into account when evaluating their responses, since an emotionally unstable person is more likely to report work and family distress generally.
But on a more fundamental level, Pugh thought the research was important because it accurately describes emotional labor as the difficult, draining work it is.
"The big point of all of this work on 'emotional labor' -- being friendly and pleasant and upbeat as part of your job -- is that it is work," wrote Pugh to HuffPost. "It is hard, and it drains people just like physical or mental labor might. But it is often unrecognized as 'real' work, so people don't appreciate the difficult nature of this kind of 'labor.'"
The sooner employers get on board with the notion of emotional labor as real work, the sooner they can start adequately compensating or rewarding workers for it, Pugh explained.
"Many skilled service workers take pride in their ability to use their emotions to manage and control difficult customers, much like a detective might take pride in his or her ability to use various emotion management strategies to manipulate criminal suspects," Pugh explained. "Managers can also recognize these legitimate job demands, and the skills they require, and compensate appropriately."
Once employers acknowledge the toll of emotional work, they can help their employees cope with simple changes like providing "offstage" areas for employees to relax and drop the mask, or training them about how pleasant behavior is a strategy that benefits them and the company.
"Good managers let employees know when it is OK to break character and drop the positive demeanor," said Pugh. "Good managers also provide the support for employees so that the stresses of working customer-facing jobs don't bleed over as much into the home."
Of course, if that's too hard, employers could simply drop the requirement to be a shiny, happy person all the time, said Wagner.
"In some countries there are no norms around faking positive displays (and those might just be the countries about which American tourists complain!), but the norm in the U.S. tends to be service with a smile," Wagner acknowledged.