Does laughter increase tolerance of pain?

Behind the Headlines

Wednesday September 14 2011

The methods used to measure pain were weak

“Study reveals laughter really is the best medicine,” reports BBC news. Several newspapers covered this small study investigating the effect of laughter on pain tolerance.

The study found that people who were made to laugh by watching comedy videos had higher pain thresholds immediately after the videos than before. They also had significantly higher pain thresholds than groups that were shown unfunny, factual videos. The higher pain threshold was seen only when people were laughing in groups, and laughing alone had no effect on pain tolerance.

This small study has several limitations relating to its design and how it was carried out. The methods that were used to measure the participants’ pain thresholds were particularly weak. As such, larger studies with more accurate and reliable measures of pain will be needed to confirm these findings.

It is also worth pointing out that the aim of this research was to investigate how laughter may play a role in social bonding and its relationship to the release of endorphins in the body. It did not look at whether or not laughter can be beneficial as pain relief in a medical context.

 

Where did the story come from?

The study was carried out by researchers from the University of Oxford in collaboration with other European and US researchers. It was funded by the British Academy Centenary Research Project.

The study was published in the peer-reviewed scientific journal Proceedings of the Royal Society B.

This story was generally accurately reported in the media, although the news reports may have given the impression that these findings have more medical significance than they do.

 

What kind of research was this?

This research was a series of six experimental studies carried out in people in both the laboratory (watching videos) and in more natural settings (such as watching stage performances).

It aimed to investigate the link between relaxed social laughter and feelings of wellbeing and the role laughter plays in social interaction between people. Specifically, the researchers wanted to know whether the physical act of laughing generates feelings of wellbeing and what the biological explanation for this might be.

The researchers wanted to test the theory that the feelings of wellbeing associated with laughter are caused by the release of chemicals called endorphins. These chemicals, released during activities such as exercise and excitement, are known to make people less sensitive to pain and, in monkeys, are thought to play a central role in social bonding. In this study, the researchers chose to measure endorphin levels in an indirect way by assessing participants’ sensitivity to pain.

 

What did the research involve?

This research involved a series of six experimental studies in both the laboratory (watching videos) and in more natural settings (watching stage performances). The participants’ pain thresholds were assessed before and after the video or performance sessions.

In five experiments, participants watched either a comedy video (experimental group) or a non-humorous factual documentary (control group). Some participants watched the videos on their own and not as part of a group. In the sixth study, participants were drawn from the audience of comedy shows at the Edinburgh fringe festival and compared with audience members from non-comedy stage shows. The number of participants in each of the six experiments ranged from 16 to 62 adults who were often split into smaller subgroups.

How frequently the participants laughed during the video sessions was recorded by microphone and measured for both individuals who were tested alone and for those in groups. Those who watched stage performances were asked to complete a questionnaire of how much they laughed during the performance on a 0-5 scale.

The researchers used pain thresholds as an indirect measure of endorphin release and tested participants both before and after they had watched the video or the stage show. In two of the six experiments, pain thresholds were measured by seeing how long participants could stand the pain of having their forearms in a cold (-16ºC) wine cooler sleeve. During these experiments, however, the researchers became concerned that following the video showing, the sleeves were less cold than before. In the remaining experiments, they tested pain tolerance by inflating a mercurial sphygmomanometer (the inflatable cuff typically used to measure blood pressure) until the participant could not tolerate the pain and recorded the maximum pressure value. They reported that this cuff pain test gave less varied results than the cooler sleeve – an indicator that it was possibly a more reliable test.

Participants who watched the stage performances were asked to lean against a wall with legs bent at right angles until it became too painful and they collapsed.

Participants who were pregnant, diabetic, suffering a medical condition or who had drunk alcohol or smoked within two hours prior to the experiment were excluded.

The researchers tested for statistically significant changes in pain threshold in 16 different scenarios (combinations of group and solitary tasks) drawn from the six experiments.

 

What were the basic results?

The researchers found that pain thresholds were significantly higher after watching comedy videos compared with before, and that no change was seen in those who had watched factual videos. This increase in pain threshold was only seen when participants watched the videos in a group. Laughing when watching alone was not associated with any increase in pain threshold.

Participants who were shown videos that made them feel good, but did not cause laughter (such as pleasant scenes of nature and animals from a wildlife documentary), did not experience significant changes in pain threshold. They say this indicated that the change in pain threshold was associated with the act of laughing rather than associated with a general “feel good factor” gained from the videos.

People who watched live comedy performances laughed significantly more than those watching live non-comedy dramas, and experienced an increase in their pain threshold after the performances. The pain threshold of those watching dramas did not increase after watching the show.

 

How did the researchers interpret the results?

The authors concluded that, after laughter, “pain thresholds are significantly increased, whereas when subjects watched something that does not naturally elicit laughter, pain thresholds do not change”.

 

Conclusion

This study suggests that the physical act of laughter is associated with an increase in pain threshold and indirectly suggests that this is caused by the release of endorphins. The following should be considered when interpreting this research:

  • It is unclear how accurate the researchers’ methods were at assessing pain thresholds. The researchers reported that they were concerned about the reliability of the wine cooler sleeve method, which they subsequently changed to a blood pressure cuff. Inaccuracy in measuring pain thresholds could have introduced error into the results. Further studies should use reliable and validated measurements of pain to minimise this effect.
  • Pain was used as an indirect measure of endorphin level. Ideally, the researchers would have measured pain and endorphin level together in some participants to confirm that this link existed.
  • The numbers of adults involved in each of the experiments were relatively small (between 16 and 62) and these numbers reduced even more when groups were split into smaller groups. Therefore, it is not possible to be sure that these small groups are representative of the general population. Larger studies will be needed to see whether these findings can be replicated and can be generalised to the wider population.
  • Participants who were pregnant, diabetic, suffering a medical condition or who had drunk alcohol or smoked within two hours prior to the experiment were excluded. The effect of laughter in these groups is therefore uncertain and may be different from those tested in this research.

This small study has several limitations relating to its design and how it was carried out. The methods that were used to measure the participants’ pain thresholds were particularly weak. As such, larger studies with more accurate and reliable measures of pain will be needed to confirm these findings.

The theory that the higher pain threshold was due to endorphin release will also need further testing, as endorphin levels were not measured directly in this study.

It is also worth pointing out that the aim of this research was to investigate how laughter may play a role in social bonding and its relationship to the release of endorphins in the body. It did not look at whether or not laughter can be beneficial as pain relief in a medical context.

Links to the headlines

It’s no joke – a belly laugh really is good for you. Daily Express, September 14 2011

Laugh... and it won't hurt as much! Having a giggle helps combat pain. Daily Mail, September 14 2011

Study reveals laughter really is the best medicine. BBC News, September 14 2011

Links to the science

Dunbar RIM, Baron R, Frangou A, et al. Social laughter is correlated with an elevated pain threshold. Proceedings of the Royal Society B, Biology: Published online before print September 14

 

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Analysis by Bazian

Edited by NHS Choices