Energy expenditure of genuine laughter

Abstract

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 min of laughter per day could increase total EE by 40–170 kJ (10–40 kcal).