It's all about Ying and Yang in Chinese cooking. This tea is meant to 'cool' your body from excessive Yang. The lack of sleep, hot weather, too much 'heaty' food such as BBQ and deep fried stuff could all cause a inbalance of Ying and Yang. This is 'the cure':-)
Brush the water chestnuts clean and cut off all the skin. Cut off all the yellow bits. Boil the skins for about 10 minutes and add rock sugar to taste, serve hot or cold. The remaining water chestnuts can be kept in the fridge for several days and are served raw as a fruit separate from the tea.