In the Body

Metabolism 

Psychological and Physical Effects

Why is caffeine such an integral part of our daily lives?

The simple answer, brain chemistry. The molecules caffeine and adenosine, one of the  chemicals made in the body to regulate the sleep-wake cycle, have similar molecular structures. (The article “How Sleep Works” explains adenosine’s impact on sleep in more detail.) Because the two have similar structures they form an antagonist relationship, where caffeine binds to adenosine receptors in the brain. When caffeine binds to these sites it inhibits adenosine from binding, directly fighting fatigue and making you feel more awake.

As more caffeine molecules bind in the brain more neurons begin to fire, setting off an “emergency mode” in the body.  Hormones are released that alert the adrenal glands to release adrenaline, the “fight or flight hormone.” While in an excited mode your pupils dilate, airways open, the heart beats faster, the blood flow to the major muscle groups increase as does your blood pressure. This explains why your heart “races” and a case of the “jitters” immediately follow caffeine consumption.

Like adenosine, dopamine is a neurotransmitter that activates pleasure centers in certain parts of the brain. Much like heroin and cocaine, caffeine increases dopamine levels, increasing perceived happiness and comfort.  Recent research supports the connection between dopamine and caffeine addiction because of the increased levels of the “feel good” molecule.

It is easy to see how the body can become dependent on caffeine. It makes you feel more alert by blocking adenosine. Gives you an immediate “boost” by adding adrenaline into your system, and increases your “feel good” sensation by increasing dopamine levels.

The Cycle of Caffeinism

Similar to growing accustomed to consuming certain foods or routine activities our bodies become used to consuming caffeine. After continuously drinking or eating products containing caffeine for an extended period of time the body begins to develop a tolerance. As one develops a tolerance for caffeine they will need to consume more caffeine to stimulate his or her brain and fight fatigue. The need to continuously consume more caffeine triggers caffeine’s drug like properties and creates an addictive cycle known as caffeinism.

The diagram below explains how the amount of caffeine consumed has a direct impact and influence on an individual.

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