Left: Real smile, Right: Fake smile.
Putting on a bright face at work could leave you feeling miserable.
Workers who fake a smile to keep their customers and colleagues happy could be making themselves depressed.
A new study says that fake smiling on the job actually worsens a person's mood and could even cut work productivity.
However, workers who are genuinely happy and smile as a result of positive thoughts like a upcoming holiday or a memorable family occasion improve their mood, withdraw less and are more efficient at work.
The research contradicts the policies of many firms whose customer-facing staff are instructed to appear cheery at all times.
They include employees of public transport firms, shops, banks, call centre workers and others who have face-to-face contact with members of the public as part of their job.
Lead researcher Brent Scott, an assistant professor of management at Michigan State University in the U.S. said: 'Employers may think that simply getting their employees to smile is good for the organisation, but that's not necessarily the case.
'Smiling for the sake of smiling can lead to emotional exhaustion and withdrawal and that's bad for the organisation.'
For the study, which appears in the current issue of the Academy of Management Journal, Prof Scott and colleague Christopher Barnes studied a group of bus drivers over two weeks.
They examined the effects of surface acting, or fake smiling, and deep acting, or cultivating positive emotions by recalling pleasant memories or thinking about their current situation in a more favourable way.
The study is one of the first of its kind to examine emotional displays over a period of time while also delving into gender differences.
The results were more defined for women bus drivers, the study found.
Prof Scott said: 'Women were harmed more by surface acting, meaning their mood worsened even more than the men and they withdrew more from work.
Read more: dailymail
This contradicts something I heard long ago, that your emotions will follow your body if you smile.