Caffeine is probably the most commonly used chemical stimulant. More than 90% of Americans consume caffeine on a daily basis in their coffee, soda, tea, or chocolate. Pure caffeine is a white bitter-tasting powder that can be extracted from coffee, tea, the guarana berry, or from other sources.
Caffeine is a brain stimulant. It works in the brain by blocking the natural effect of adenosine on the nerve cells, causing increased mental activity. It also causes the body to release adrenaline, which causes the heart to beat faster, blood pressure to rise, muscles to tighten up, and extra sugar to be released into the bloodstream for a burst of energy. This is why it is often used to counteract sleepiness.
Caffeine is an addictive substance. When the effects from caffeine wear off, the feelings of fatigue, depression, and irritability set in. Taking more caffeine can counteract these feelings, but this leads to a dangerous cycle. With prolonged use, it can interfere with the brain’s ability to reach deep sleep and become fully rested, which means that the person will feel tired in the morning and be more inclined to take even more caffeine.
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