<unk>  is the condition of having a substance dependence on<unk> , a commonplace central nervous system stimulant drug which occurs in nature in coffee, tea, yerba mate, cocoa, and other plants.<unk>  is also an additive in many consumer products, including beverages such as<unk> ted alcoholic beverages, energy drinks, colas.<unk> 's mechanism of action is somewhat different from that of cocaine and the substituted amphetamines;<unk>  blocks adenosine receptors A1 and A2A. Adenosine is a by-product of cellular activity, and stimulation of adenosine receptors produces feelings of tiredness and the need to sleep.<unk> 's ability to block these receptors means the levels of the body's natural stimulants, dopamine and norepinephrine, continue at higher levels. The Diagnostic and Statistical Manual of Mental Disorders describes four<unk> -related disorders including intoxication, withdrawal, anxiety, and sleep. Molecular structure of<unk>
Caffeine dependence
Nicotine dependence
Barbiturate dependence
Foreign accent syndrome
Exercise addiction
Caffeinism
Sleep paralysis
Gigantism