In Traditional Chinese Medicine (TCM), Zhang Nao belongs to the 'Herbs that open the Orifices' category. The functions of these herbs are much more platonic than the name implies. They're used to help treat conditions associated with central nervous system collapse, including strokes and coma.

Furthermore Zhang Nao is Warm in nature. This means that Zhang Nao tends to help people who have too much 'Cold' in their body, although with less effect than a plant that would be Hot in nature. Balance between Yin and Yang is a key health concept in TCM. Those who have too much Cold in their body are said to either have a Yin Excess (because Yin is Cold in nature) or a Yang Deficiency (Yang is Hot in Nature). Depending on your condition Zhang Nao can help restore a harmonious balance between Yin and Yang.

Zhang Nao also tastes Pungent. The so-called 'Five Phases' theory in Chinese Medicine states that the taste of TCM ingredients is a key determinant of their action in the body. Pungent ingredients like Zhang Nao tends to promote the circulations of Qi and Body Fluids. That's why for instance someone tends to sweat a lot when they eat spicy/pungent food.

The tastes of ingredients in TCM also determine what Organs and Meridians they target. As such Zhang Nao is thought to target the Heart. In addition to regulating Blood flow, in TCM the Heart is believed to be the store of the 'Mind' which basically refers to someone's vitality.