Smiling regularly may do more than lift your mood. It can also help build friendships, reduce stress and improve your overall well-being, experts say.
Rather than waiting for something funny or exciting to happen, simply changing your facial expression by turning a frown into a smile may influence how you feel emotionally.
Research supports the idea that smiling can affect mood, although its effects may vary from person to person.
Jeanne Tsai, a longtime psychology professor at Stanford University who leads its Culture and Emotion Lab, said earlier studies have explored the "facial feedback hypothesis", which suggests that facial expressions can influence emotional experiences.
In a well-known experiment conducted in the late 1980s, researchers asked participants to hold a pencil between their lips in a way that produced either a smiling or frowning expression while watching a positive video clip, such as a cartoon. Some participants who adopted a smiling expression reported feeling more amused.
"When we've done that demonstration in classes, it works," Tsai said.
She suggested that smiling alone, without any social interaction, might also remind people of pleasant experiences and help improve their mood.
The benefits of smiling are also reflected in educational settings. The Orange County Academy of Sciences and Arts (OCASA), a charter school group in Southern California, promotes smiling as part of its educational philosophy.
"Smiling creates a supportive classroom culture that makes students relaxed, active, and motivated," the group's website says. It adds that smiling can improve emotional well-being, reduce stress and boost students' confidence.
How smiling may benefit health
Judy Ho, a clinical and forensic neuropsychologist in Los Angeles who also teaches at Pepperdine University, recommends smiling as one possible coping strategy for some patients experiencing depression or anxiety.
"I'm not suggesting that that's the only way they can fix things," Ho said. "It's just like another thing that you can add to your toolbox."
According to Ho, smiling may influence cortisol, a hormone involved in the body's stress response and other functions related to mood regulation. It may also affect brain chemicals associated with positive feelings, including endorphins, dopamine and serotonin.
"People who smile during stressful tasks generally demonstrated lower heart rates during recovery than those maintaining neutral expressions," Ho said. "Smiling also reduced aspects of the body's physiological stress response."
The idea is that regularly smiling may eventually help people experience more positive emotions.
"In some ways it's like a mediating effect," she added.
The meaning of a smile varies across cultures
The way people interpret a smile, including how wide or expressive it is, differs across cultures.
Tsai has studied how American culture often places a strong emphasis on positive emotions while encouraging people to minimise negative feelings such as sadness. In many East Asian cultures, emotional balance is considered more important.
"It's like the positive and the negative emotions are braided together, and so you don't want to feel too positive or too negative," Tsai said. "You want more of a balance between the two."
Her earlier research compared how European Americans and people from East Asian communities, including Taiwan, South Korea, Japan and Hong Kong, perceived neutral or calm smiles and broad, excited grins.
Participants rated different facial expressions based on how warm and trustworthy they appeared. While some Americans viewed more expressive smiles as a sign of friendliness, some East Asian participants considered such expressions emotionally unstable or unreliable.
"What kind of smile matters — whether it's a calm, closed-mouth smile more like the Dalai Lama or a big toothy excited smile like Julia Roberts," Tsai said.
She noted that research in Taiwan and other East Asian settings found that people generally did not favour broad, toothy smiles unless the situation called for them.
In Thailand, often known as the "Land of Smiles", smiling is deeply rooted in the culture. The Thai language has nearly 30 words for different types of smiles.
Many programmes that send people to Thailand to teach English as a foreign language also emphasise the importance of smiling at children and colleagues as a way of showing respect, good manners and calmness.
At OCASA charter schools, smiling is encouraged as part of an effort to help children feel acknowledged and supported.
"I've always believed in wanting school to be a happy place for kids," said RaNae Posey, principal of OCASA Capistrano Elementary School.
She said the goal is to help children develop the habit of looking at the brighter side of things.
Forced smiles may have the opposite effect
Despite its potential benefits, smiling does not always make people feel better, particularly when they are pressured to do it.
In recent years, women have challenged workplace expectations that require them to smile, arguing that such demands are often applied differently to men. Women and people of colour may also face stereotypes that portray them as cold or unapproachable when they do not smile enough.
Last year, retailer Target faced criticism on social media after introducing a policy requiring employees to smile and make eye contact when customers were within 10 feet (3 metres). Workers were also expected to greet customers personally when they came within 4 feet (1.2 metres).
Nicholas Coles, an assistant professor who leads the Social Science Collaboratory at the University of Florida in Gainesville, said people generally dislike feeling that they have lost control over their own emotions.
"In those scenarios, what we find is that it's more that you're smiling your way to misery," Coles said. "It's only when it feels authentic and voluntary that I think it'll have any real effect."
As the holiday season approaches, people may also feel pressure to smile and remain pleasant during family gatherings, particularly when sensitive subjects such as politics and religion arise.
Ho suggested that choosing to smile during difficult conversations could help people respond more positively to relatives and loved ones.
"If we were able to just smile and be like 'Look, this is somebody that historically cares about you and loves you,' maybe that would change the way that we respond to them even in a moment of tough conversation," she said.