What are the factors in' black tea and green tea' that make people unable to sleep after drinking it and unable to sleep at all before going to bed? Why?

Many people are afraid to drink tea because they are afraid of not being able to sleep at night. Professor Jiang Heyuan from the Tea Research Institute of China Academy of Agricultural Sciences told us that tea has both refreshing and nourishing effects, which can not only make the brain more awake and flexible, but also inhibit the excessive excitement of the brain and make people fall asleep easily. It depends on how you drink.

Caffeine and tea polyphenols in tea have the greatest influence on brain nerves. Tea leaves are soaked for about 2 minutes, and about 70%-80% of caffeine is dissolved in water. At this time, tea has obvious refreshing effect and makes people excited. After that, the tea polyphenols in tea gradually dissolve in water, which counteracts the effect of caffeine, so it is not easy to cause obvious physiological excitement. Therefore, when drinking tea at night, as long as you pour out the first tea that has been soaked for about 2 minutes, and then add boiling water to soak it again, the refreshing effect will not be so obvious.

Professor Jiang also suggested that everyone had better drink black tea in the evening. Because green tea belongs to non-fermented tea, it has high content of tea polyphenols, maintains its original properties and is irritating; Black tea is a completely fermented tea. Although the content of tea polyphenols is low, it is mild after "aging" and suitable for drinking at night. Especially for people with weak spleen and stomach, adding some milk when drinking black tea can play a certain role in warming the stomach.

However, people who are easily excited or sensitive, have poor sleep and are weak should drink less or not drink tea at night. In addition, when drinking tea at night, you should put less tea leaves and don't make the tea too strong. It is best to drink tea after meals, because drinking tea on an empty stomach will harm your health, especially for people who don't drink tea often, it will inhibit the secretion of gastric juice, hinder digestion, and seriously cause palpitations, headaches and other "tea drunk" phenomena.