Joy is a healthy emotion. It increases Heart-Yang. But a high level of joy cannot be sustained for long. It exhausts and disperses.

The pathological version of this emotion would be a manic, over-excited, euphoric, reckless state that over-stimulates the Shen and damages the Heart. In the long term it can consume Heart-Yin, which does not control Yang. It can cause palpitations, insomnia, startles, talks a lot, cannot stay still. It has difficulty concentrating, changes tasks every 5 minutes. It is in continuous search for stimuli and avoids solitude.

Pathological euphoria is stronger if it is sudden or unexpected: good news can feel similar to a shock.

Lack of joy is also pathological: when we experience too many sadnesses and fears, especially in childhood, Heart-Yin and Yang can be damaged. Inability to love, addictions, dissatisfaction. See depression.