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 minutes of laughter per day could increase total EE by 10–40 kJ (2–10 kcal) [corrected].

Figure 1

A sample output of simultaneous measurement of laughter energy expenditure (EE) (Laughter EE (kcal/min)=EE during laugh − EE at rest), heart rate (HR (beats/min)=HR during laugh − HR during rest), and laughter duration (s/min) during episodes of laughter evoked by viewing film clips in a male dyad. Periods when humorous film clips were viewed are marked on the time line.

Figure 2

Body weight (kg) in dyads. Each point represents one dyad. Pearson’s correlation between individuals in dyads was significant (r=0.339, P=0.020).

Figure 3

Laughter energy expenditure (EE) (Laughter EE (kcal/min)=EE during laugh − EE at rest) during viewing film clips unlikely to evoke laughter (non-humorous) and evoking laughter (humorous) in 45 dyads of young adults during 90min session conducted in a whole-room indirect calorimeter. Error bars show 95% confidence interval of mean.

Figure 4

Laughter energy expenditure (EE) calculated as a difference between EE at rest and during viewing humorous film clips intended to evoke laughter (Laughter EE (kcal/min)=EE during laugh − EE at rest) and laughter heart rate (laughter HR) calculated as a difference between HR at rest and during viewing humorous film clips intended to evoke laughter (Laughter HR (beats/min)=HR during laugh − HR during rest) divided into quartiles by laughter duration (s/min).