Laughter as Modulator of Stress: Lefcourt et al. Study
Boone, Hansen, and Erlandson examined the cardiovascular responses to laughter (2000). Eight volunteer subjects rested for five minutes (Control #1), watched a videotape of Robin Williams telling humorous jokes for five minutes (Treatment), and rested for five more minutes (Control #2). Oxygen consumption was measured using a Medical Graphics CPX/D metabolic analyzer and was averaged for each set of five minutes. Cardiac output was ascertained during the last minute of each period using the CO2 rebreathing technique. Heart rate and blood pressure were determined in the last 10 seconds of each minute. Finally, arteriovenous oxygen difference (O2 consumption/cardiac output), mean arterial pressure [1/3*(SBP-DBP)+DBP], stroke volume (cardiac output/HR) and total peripheral resistance (mean arterial pressure/cardiac output) were calculated.
Between Control #1 and treatment, stroke volume and cardiac output significantly increased (p<.05), while arteriovenous oxygen difference and total peripheral resistance significantly decreased (p>.05). From treatment to Control #2, O2 consumption significantly decreased; changes in the variables were not significant. From Control #1 to Control #2, stroke volume and cardiac output significantly increased, and O2 consumption, arteriovenous oxygen difference, and total peripheral resistance significantly decreased. Boone et al. explain that, though stroke volume increases led to cardiac output increases, oxygen consumption did not change because use of delivered oxygen (arteriovenous oxygen difference) was decreased (2000). They suggest that lighting, circumstances, or other variables may explain that their study did not find increased HR that had been shown previously. This study does have limitations. The subjects volunteered rather than being randomly selected. Boone et al. point out that they did not control for the subjectivity of humor, nor did they record length, frequency, or intensity of laughter. In addition, the sample size is quite small, though the results reported were significant based on p-tests and analysis of various (ANOVA) tests (Boone et al., 2000).
Alternative Medicine | Laughter
Laughter as a Stress Modulator | Physiologic Effects of Laughter | Applications of Humor in Medicine