Life Course and Health

―The Associations of Laughter with Stress and Lifestyle-related Diseases―

Abstract

Our health is influenced by lifestyle and various types of stress from birth until death. However, it is generally hard to reduce stress in life. On the other hand, recent studies show that positive emotions and behavior act as a buffer against psychological stress and negative emotions. We think that laughter is a modifiable factor because laughter is “behavior”, not “emotion”. We examined 4, 780 men and women in two distinct localities and characterized the frequency of laughter according to sex and age. It turned out that women tended to laugh more often than men and the frequency of laughter declined with age. Furthermore, the low frequency of laughter was associated with a decrease in cognitive function and a high risk of developing diabetes mellitus. We also researched the effects of rakugo (comic storytelling) on salivary cortisol levels, a biomarker of stress. It was discovered that mean salivary cortisol levels of participants who would laugh often or “every day” decreased significantly after watching rakugo. Therefore, laughter is considered to be potentially effective for prevention and management of a variety of diseases, including both stress-related and lifestyle-related diseases.