Laughing every day may help keep the heart healthy but depression can lead to heart failure, according to two new studies (Laughter May Be Good for the Heart, Study Finds).

This can be explained by Chinese medicine, which believes that organs and emotions are interrelated. The heart, for instance, is related to joy and happiness. A person with a healthy heart is more likely to feel these emotions than a person with a deficient heart, and the greater the deficiency, the less joy and happiness. When these emotions are completely absent, there is depression; in the Chinese medicine view, depression means that the heart is severely deficient — in other words, there is a risk of heart failure. This also explains why Chinese medicine treats depression by enhancing the heart.

Chinese medicine also believes that the interrelationship between organs and emotions works both ways: not only can organs affect emotions, but emotions can also affect organs. This is why laughter, which is the simplest way of increasing joy and happiness, enhances the heart. Fifteen minutes of laughter a day, as the study recommends, is therefore valuable for many or most of us, but is best avoided by people who suffer from over-excitement, which is a reflection of an overly active heart that doesn’t need further stimulation.

A more technical explanation for the interested reader: Depression is unhappiness, which is a case of Deficient Fire and therefore requires enhancing the heart. Laughter increases Fire, but over-excitement is a case of Excessive Fire which needs to be reduced.