Even in the hardest of times, laughter has a steadfast ability to bring people together. A new study reveals how laughter affects the brain, which may help to explain why having a giggle plays such an important role in social bonding.
Researchers from Finland and the United Kingdom found that social laughter triggers the release of endorphins - often referred to as "feel good hormones" - in brain regions responsible for arousal and emotion.
Endorphins are peptides that interact with opioid receptors in the brain to help relieve pain and trigger feelings of pleasure.
What is more, the study revealed that the more opioid receptors people have in brain regions associated with the processing of emotions, the more they engage in social laughter.
"Our results highlight that endorphin release induced by social laughter may be an important pathway that supports formation, reinforcement, and maintenance of social bonds between humans," says study co-author Prof. Lauri Nummenmaa, of the Turku PET Centre at the University of Turku in Finland.
The researchers recently reported their results in The Journal of Neuroscience.
Social laughter led to increase in endorphins
Prof. Nummenmaa and colleagues enrolled 12 healthy men to their study.
Participants were injected with a radioactive compound that adheres to opioid receptors in the brain. Using positron emission tomography (PET) imaging, the researchers were then able to monitor the release of endorphins and other peptides that bind to opioid rectors.
Participants underwent PET scans twice. The first scan was conducted after each participant spent 30 minutes alone in a room, and once after they spent 30 minutes watching laughter-inducing video clips of their close friends.
The researchers found that the social laughter condition led to a significant increase in endorphin release in the thalamus, caudate nucleus, and anterior insula regions of the brain. These are brain regions that play a role in arousal and emotional awareness.
Additionally, the team found that participants with a greater number of opioid receptors in the cingulate and orbitofrontal cortices of the brain were more likely to laugh in response to their friends' video clips.
The cingulate cortex is involved in the processing and formation of emotions, while the orbitofrontal cortex is involved in a number of emotion-related processes.
Endorphins might 'promote feelings of togetherness'
The researchers say that their results indicate that the release of endorphins triggered by laughter might play a role in social bonding.
"The pleasurable and calming effects of the endorphin release might signal safety and promote feelings of togetherness," says Prof. Nummenmaa. "The relationship between opioid receptor density and laughter rate also suggests that [the] opioid system may underlie individual differences in sociability."
Study co-author Prof. Robin Dunbar, of the University of Oxford in the U.K., adds that the results highlight the importance of vocal communication in social bonding.
"Other primates maintain social contacts by mutual grooming, which also induces endorphin release. This is however very time-consuming.
Because social laughter leads to similar chemical response in the brain, this allows significant expansion of human social networks: laughter is highly contagious, and the endorphin response may thus easily spread through large groups that laugh together."
Prof. Robin Dunbar
While further research is needed to confirm these findings, the study certainly provides an excuse to have a chuckle with friends this weekend.