How Does Caffeine Work?


Quick Answer

Caffeine functions by stimulating the central nervous system, which affects the heart and blood pressure, by blocking adenosine, a natural chemical found in the brain that regulates sleep. Adenosine connects to receptors in the brain and slows down the activity of the cells; drowsiness results. Caffeine works to keep an individual alert by taking over the receptors and increasing their speed, which has the opposite effect of adenosine.

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Full Answer

Because it causes blood vessels to constrict and blocks adenosine, caffeine causes the pituitary gland to send signals to the adrenal gland to release adrenaline. Adrenaline is responsible for the body’s fight or flight reaction and causes a faster heartbeat, dilation of the pupils, increased blood flow to the muscles, and reduced blood flow to the body surface and stomach. It tightens muscles and signals a release of sugar from the liver into the blood. Caffeine exists in cola drinks, tea, coffee, energy drinks and other products.

Because of the body’s reaction to caffeine, it has many uses other than improving alertness. Physicians use caffeine to treat migraines in conjunction with painkillers and to treat asthma, low blood pressure and gallbladder problems. They also use it to promote weight loss. Applying caffeine creams to the skin is a treatment for dermatitis, itching and skin redness.

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