While many of us instinctively believe that smiling can make us feel better, the theory has long been questioned by academics.
But now, a new study suggests that turning that frown upside down can improve your mood.
For the study, published in the journal Psychological Bulletin, American psychologists analysed nearly 50 years of data from more than 100 studies that each tried to determine whether facial expressions can affect people’s moods.
The studies, which included more than 11,000 people worldwide, concluded that smiling does makes people feel happier, while scowling makes them feel angrier, and frowning makes them feel sadder.
Lead researcher Nicholas Coles, a University of Tennessee PhD student, says: “Conventional wisdom tells us that we can feel a little happier if we simply smile. Or that we can get ourselves in a more serious mood if we scowl.”
”But psychologists have actually disagreed about this idea for over 100 years.”
The research team explained that controversy surrounding the theory became heightened in 2016 when 17 teams of researchers failed to replicate a well-known experiment showing that smiling can make people feel happier.
“Some studies have not found evidence that facial expressions can influence emotional feelings,” Coles says
“But we can't focus on the results of any one study. Psychologists have been testing this idea since the early 1970s, so we wanted to look at all the evidence.”
As a result, the team of scientists set out to gather a much bigger pool of data, using a statistical technique called meta-analysis - the examination of data from a number of independent studies of the same subject - to combine data from 138 global studies.
And, according to the results of the meta-analysis, facial expressions do have an impact on feelings.
While Coles describes the results as “exciting”, he points out that the impact of smiling on feelings was small, meaning the research should not be used as a way to treat mental health conditions like depression.
“We don't think that people can smile their way to happiness,” he said.
“But these findings are exciting because they provide a clue about how the mind and the body interact to shape our conscious experience of emotion.
“We still have a lot to learn about these facial feedback effects, but this meta-analysis put us a little closer to understanding how emotions work.“
The study was published in the journal Psychological Bulletin.