Need info on what causes an opposite reaction of caffeine makes me very tired immediatly.

I know the answer is to not take it and i avoid it, but i know others have the same problem and would like to know how it works on the brain. I also read an article before that people with attention disorders are more prone to this type of reaction to caffeine. I do have problems in my attention at times that have prevented me from acheiving things in life. Does anybody know any articles on this rarer reaction to caffeine.

[Dr Santos]

Hi,
How are you? Caffeine is useful as a cardiac stimulant and causes the blood vessels to constrict, hence increasing the firing of neuron in the brain. Experts say that too much caffeine can actually have the opposite effect on people and make them feel even more tired. People who drink coffee regularly build up a tolerance to caffeine. Having too much caffeine or caffeine toxicity may lead to anxiety attacks, nervousness, rapid heart beat and nausea. Here is a link to one study showing the relationship of taking high intake of caffeine and feeling tired in the morning and having difficulty sleeping especially in adolescents (http://www.sciencedirect.com/science/article/pii/S1054139X05002582)
Take care and regards.