Caffeine is a mild stimulant.

Caffeine is a mild stimulant and is found in smaller amounts in our daily beverages such as tea, cocoa and chocolate. Caffeine is also found in carbohydrate drinks such as cola and certain narcotics. It can speed up the metabolism of the human body and keep people clear-headed and alert. So there are a lot of wonderful little white collar workers who need to stay up late to get coffee to refresh themselves.

Caffeine can stay in the body for hours, and its effects on the body vary from person to person. Some people drink coffee at night will insomnia, some people drink too much coffee, will be nervous, excessive excitement, but there are also many people will not be affected at all, this is determined according to everyone's body reaction to caffeine, like Xiaobian has been accustomed to drinking coffee, ordinary instant coffee has not been able to play a refreshing role.

Caffeine in coffee is insoluble in cold water, but soluble in hot water. It stimulates the cerebral cortex, eliminates drowsiness, enhances touch and thinking, and adjusts heart function, as well as dilating kidney blood vessels and diuretic effects. However, caffeine is not limited to coffee, usually a 100cc cup of coffee contains 60 to 65mg of caffeine, green tea has 200 to 300mg, black tea has 350 to 400mg, cocoa has about 100mg. Too much caffeine can lead to tinnitus, hyperactivity (rapid heartbeat, increased pulse rate), and uneven pulse rate, so some people are not suitable for drinking coffee.