Energy expenditure of genuine laughter.

OBJECTIVE

To measure energy expenditure (EE) and heart rate (HR) during genuine laughter.

DESIGN

Experimental trial of viewing film clips in four cycles either intended to evoke laughter (humorous -10 min) or unlikely to elicit laughter (not humorous -5 min) under strictly controlled conditions of a whole-room indirect calorimeter equipped with audio recording system.

PARTICIPANTS

Forty five adult friend dyads in either same-sex male (n=7), same-sex female (n=21) and mix-sex male-female (n=17); age 18-34 years; body mass index 24.7+/-4.9 (range 17.9-41.1).

MEASUREMENTS

Energy expenditure in a whole-room indirect calorimeter, HR using Polar HR monitor. Laugh rate, duration and type from digitized audio data using a computerized system and synchronized with HR and EE results.

RESULTS

Laughter EE was 0.79+/-1.30 kJ/min (0.19+/-0.31 kcal/min) higher than resting EE (P<0.001, 95% confidence interval=0.75-0.88 kJ/min), ranging from -2.52 to 9.67 kJ/min (-0.60-2.31 kcal/min). Heart rate during laughter segments increased above resting by 2.1+/-3.8 beats/min, ranging from -7.6 to 26.8 beats/min. Laughter EE was correlated with HR (r (s)=0.250, P<0.01). Both laughter EE and HR were positively correlated with laughter duration (r (s)=0.282 and 0.337, both P<0.001) and rate (r(s)=0.256 and 0.298, both P<0.001).

CONCLUSION

Genuine voiced laughter causes a 10–20% increase in EE and HR above resting values, which means that 10–15 minutes of laughter per day could increase total EE by 10–40 kJ (2–10 kcal) [corrected].