~ Joy ~
The term “joy” should be interpreted broadly. Obviously joy is not in itself a cause of disease.
“Joy makes the Mind peaceful and relaxed, it benefits the Nutritive and Defensive Qi and it makes Qi relax and slow down”.
What is meant by "joy" as a cause of disease is obviously not a state of healthy contentment but one of excessive excitement and craving which can injure the Heart. This happens to people who live in a state of continuous mental stimulation (however pleasurable) or excessive excitement. This leads to excessive stimulation of the Heart and, in time, can lead to Heart-Fire or Heart Empty-Heat, depending on the underlying condition.
The main manifestations are palpitations, over-excitability, insomnia, restlessness, talking a lot and a red tip of the tongue.
Joy may also be marked out as a cause of disease when it is sudden; this happens, for example, on hearing good news unexpectedly. In this situation, "joy" is similar to shock.
The fairly common situation of this over excitement would be a migraine attack or, mostly in children, where over-excitement usually ends in tears.