Many people think of caffeine as something in coffee. It is also found in many other common substances. These include: Tea, cocoa, chocolate and cola. Caffeine is defined as a drug because it affects the central nervous system. It is categorised as a stimulant drug because caffeine speeds up production of nerve impulses.
Incoffee beans, caffeine content will depend on the strain of the coffee plant. The Arabic strain contains about 1% caffeine and is grown in Cetral and South America. The Robusta strain contains about 2% caffeine and is grown in Africa and Indonesia. In tea, the caffeine contents depends on the strength of the brew. Caffeine content in tea can be as high as 5%. The caffeine content in a cup of coffee,however, is usually higher than tea. This is because it takes a lot more coffee beans to make a cup of coffee than tea leaves to make a cup of tea.

History

The first historical record of Caffeine use was from Aztec records from the time of the Aztec leader Montezuma. Caffeine was taken in the form of a hot drink made with cacao (the 'chocolate' tree) leaves and various herbs and spices. Montezuma was said to have drunk up to 50 cups a day. Chocolate in the form of the chocolate bar was first introduced by the Bristol company Fry & Son in 1847. Coffee proved to be a far more popular form of caffeine intake. It is mentioned in the Koran, the holy book of the Moslem religion and originates from Africa and the Middle East. It was introduced into the UK originally as a medicine but became extremely fashionable between 1670 and 1730 when there was a massive increase in the number of coffee houses. However, coffee houses became the place to debate political and social issues and so were closed by the authorities because they were considered to be subversive. However this was extremely unpopular and in time the ban was lifted on condition that places that sold coffee were not to give out political leaflets. Tea is another source of caffeine which originates from China. It was first introduced into Europe at about 1600 and arrived in the UK about 60 years later.

Effects

The effect of caffeine on the body varies from person to person and it depends on the amount of the caffeine is taken, the way is taken, bodt's size and weight, previous usage of it, taking it with other drugs, person's mood and the circumstances in which caffeine is taken e.g. with food, in social gatherings.

Immediate effects

When taken in drink form, caffeine produces a number of mild effects on the body.

In small doses (such as a cup of coffee), caffeine:

• increases alertness
• increases urination
• increased general metabolism and body temperature
• stimulates the secretion of gastric acid.

Long-term effects

There is no evidence of caffeine producing any toxic effects if consumption is below 600mg a day. Consumption above this level may cause insomnia, anxiety, depression and stomach upsets.

Caffeine and Sleep
When is taken before going to bed, it usually:

• delays and shortens sleep
• reduces the deep sleep cycle
• increases the amount of dream sleep early in the night, but reduces it overall.

Tolerance may also develop quickly, where the user may have to drink, for example, more and more coffee to get the same 'kick' from it.

Caffeine and Pregnancy

Most drugs can affect an unborn child. Research has found that some links between very large doses of caffeine and miscarriage, premature delivery and stillbirth. This is not a problem for women who consume average quantities of caffeine during pregnancy. Doctors recommend no more than 2-4 cups of coffee or tea a day (approximately 200mg of caffeine) for pregnant women.

Ongoing Research

Ongoing research suggests that consuming above 600mg of caffeine a day may make some heart problems worse and may contribute to palpitations. Also, people with anxiety disorders (e.g.panic attack, agoraphobia) should avoid caffeine as it can make the problem worse.