In the study involving 400 scientists came to the conclusion that coffee is invigorating drink. There are a lot of amphetamine, but the effects of caffeine differ from them.
Some volunteers were asked to drink coffee during a certain time, other instead of coffee got caffeine free beverage with similar taste. Half of the subjects were not previously involved drinking coffee, others did it in moderation.
It turned out coffee gives a boost of energy only in the case of rare use. If the person is using the drink every day, addicted to coffee and ceases to invigorate the human body.