"Adenosine is an inhibitory neurotransmitter, believed to play a role in promoting sleep and suppressing arousal, with levels increasing with each hour an organism is awake. Caffeine's principal mode of action is as an antagonist of adenosine receptors in the brain. By nature of caffeine's structure it binds to some of the same receptors as adenosine. The pharmacological effects of adenosine may therefore be blunted in individuals who are taking large quantities of methylxanthines (e.g., caffeine, found in coffee and tea, or theobromine, as found in chocolate). Generalized, adenosine has an inhibitory effect in the central nervous system (CNS). Caffeine's stimulatory effects, on the other hand, are primarily (although not entirely) credited to its inhibition of adenosine by binding to the same receptors, and therefore effectively blocking adenosine receptors in the CNS. This reduction in adenosine activity leads to increased activity of the neurotransmitter dopamine." The key to immortality, found! Drink more and more caffeine every day and chase those insomnia blues away! Be the first on your block to stay awake for-everrrrr*! *TuckerLab not responsible for coma and/or death.