New research by Dr. Dieter Zapf of Frankfurt University suggests that workers who constantly have to pretend to be friendly to customers suffer from higher rates of depression and illness. The Advertiser reports:

Flight attendants, sales personnel and call centre operators are most at risk, say psychologists at Frankfurt University. People in these jobs are more likely to suffer from depression, according to the study released yesterday ahead of publication in consumer magazine Good Advice. "Every time a person is forced to repress his true feelings, there are negative consequences for his health," said Professor Dieter Zapf, a researcher into human emotions.

I'm a little surprised that it was a German professor who did this study, because it's my subjective impression that fake happy workers seem to be more of an American phenomenon than a European one. American waiters, for instance, always want to act as if they're your new best friend, whereas European waiters tend to be a little more formal in how they interact with diners. Though maybe this is changing.