Greater frequency of laughter linked to decreased stress symptoms

1. More frequent laughing was correlated to fewer symptoms of stress in university students after experiencing stressful events.

2. Intensity of laughter was not found to mediate the relationship between stressful events and symptoms of stress.

Evidence Rating Level: 2 (Good)

Study Rundown: Psychological stress has been extensively linked to numerous diseases, such as cancer, heart disease, anxiety, and depression. Symptoms of stress include feeling headaches, stomach aches, restlessness, and nervousness. However, stressful events do not affect all individuals the same way. Positive affect (defined as the inclination to experience positive emotions) is thought to mediate the relationship between stressful events and stress symptoms.

This longitudinal study analyzed self-reported data from Swiss university students. For two weeks, students were prompted 8 times daily to answer questions on an app about stressful events, stress symptoms, and laughter since the last prompt. The study found that frequency of laughter reduced the correlation between stressful events and stress symptoms. Interestingly, intensity of laughter had no effect on the interaction.

The study, relying on real life events rather than induced ones in a laboratory environment, provides greater ecological validity. However, although the longitudinal data allowed over 100 measurements per individual, the reliance on self-report data may limit the data accuracy. With only 12% of self-reports noted stressful events occurring, the data can’t be extrapolated to those suffering from chronic stress. Study findings provide evidence supporting the stress-buffering model of positive affect, and address an interesting knowledge gap in literature.

Click to read the study in PlosONE

Relevant Reading: Grin and Bear It: The Influence of Manipulated Facial Expression on the Stress Response

In-Depth [prospective cohort]: The population was psychology students at the University of Basel (n = 41). The mean age was 21.9 (SD = 3.9, Range = 19-44) and 80.5% were female. For 14 consecutive days and 8 times daily, participants were acoustically prompted to fill out a survey. The survey asked about their frequency and intensity of laughter, experience of stressful events, and experience of stress symptoms, since the last prompt. Frequency/intensity of laughter was rated on a scale, whereas stressful events were measured with a yes/no question. Two measures of stress symptoms were used: Both involved a 6-point Likert scale to rate statements. The aggregated self-report was a list of 8 stress symptoms to be rated, and the global self-report was a rating for the question “How much stress have you experienced since the last prompt?”

The standardized association coefficient between stressful events and the aggregated self-report of stress symptoms was 0.374 (95% CI 0.324-0.432); the coefficient between stressful events and the global self-report of symptoms was 0.418 (95% CI 0.372-0.464). Laughter frequency was found to moderate this correlation: For a 1 standard deviation increase in laughter frequency (relative to each individual), the association was decreased by 0.052 for the aggregated self-report. The standardized model coefficient (sCOEF) was therefore -0.052 (95% CI -0.082 to -0.021). For the global self-report, the sCOEF was -0.060 (95% CI -0.092 to -0.028). Laughter intensity was not found to moderate the relationship between stressful events and stress symptoms, as the 95% CIs included the zero value. For the aggregated self-report, the sCOEF was -0.012 (95% CI -0.020 to 0.045) and for the global self-report, the sCOEF was 0.032 (95% CI -0.002 to 0.066).

Image: PD

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