Several studies have explored the relationship between smiling and stress, showing that the physical act of smiling can influence the body’s response to stress. One study by Tara Kraft and Sarah Pressman, published in Psychological Science in 2012, found that participants who were instructed to smile during a stressful task had lower heart rates and reported feeling less stressed than those who maintained neutral expressions. 

participants were instructed to hold chopsticks in their mouths so that they activated the facial muscles associated with either a Duchenne smile, non-Duchenne smile, or neutral facial expression. All participants were given a cover story that the study was investigating multitasking so that they would not be aware that they were smiling. However, in order to manipulate awareness of expression, half of the participants were told to smile, and half were not given this instruction. Adherence to facial expression condition was coded on a 1 (poor adherence) to 5 (excellent adherence) scale and was controlled for in analyses. Regardless of whether or not participants knew they were smiling, smiling participants had lower heart rates during recovery from two stressful tasks, with a slight advantage for those who were making Duchenne smiles (Kraft & Pressman, 2012). In line with the naturally occurring smiles study conducted by Fredrickson and Levenson (1998), this study provides additional evidence that smiling during stress may be particularly helpful for cardiovascular recovery.”

This study involved participants completing stressful tasks, such as submerging a hand in ice water or performing a timed task, while holding different facial expressions. Those who smiled—especially those with a genuine, Duchenne smile (which engages both the muscles around the mouth and eyes)—experienced quicker recovery from stress compared to those who did not smile or who smiled only with their mouth.

This suggests that smiling not only has a psychological impact but also triggers physiological changes that can mitigate the effects of stress. The activation of facial muscles involved in smiling sends feedback to the brain, which in turn triggers the release of endorphins, the body’s natural feel-good chemicals. This response can create a positive feedback loop, reducing the stress response and promoting a sense of well-being.

Smiling as a stress-relief mechanism can be explained by several psychological theories. One of the most prominent is the facial feedback hypothesis, which posits that facial expressions can influence emotional experiences. According to this theory, the act of smiling can send signals to the brain that reinforce feelings of happiness and relaxation, even when the smile is not spontaneous.

Additionally, smiling can disrupt the brain’s tendency to fixate on negative emotions. By breaking the cycle of negative thinking, smiling allows individuals to reframe their stressors in a more positive light. This cognitive shift can make stressors feel less overwhelming and more manageable.