Caffeine is a very ubiquitous chemical. It is found in coffees, teas, sodas and chocolates. The caffeine content of these different things vary widely but the chemical has the same effect, to a varying degree depending on the amount consumed. Caffeine's most well known aspect is its ability to combat mental and physical fatigue. All around the United States and the world, it is the mostly widely used, legal stimulant available. Many people use it to keep working through fatigue and others use it to wake up in the morning.
Discovered in 2737 BCE by Emperor Shen Nung, tea is credited as being the first caffeinated beverage. Emperor Shen Nung was drinking hot water under a tea tree when a leaf fell into his drink. Shen Nung is mentioned to have said that a fragrant and restorative drink resulted from this chance encounter .Coffee was rumored to be discovered by an Egyptian goat herder named Kaldi, who noticed his goats being anxious. Kaldi noticed his goats eating red berries, when Kaldi tried the berries he too became invigorated. Kaldi later collaborated with local monks to make a drink out of the berries, coffee then began to spread and became popular throughout the Arabian world. The late 17th Century saw the growth of tea, but it wasn't until the late 19th Century when caffeine was isolated. Emil Fischer, a Nobel Prize winning German chemist, was the first to isolate caffeine (C8H10N4O2) from the plant in 1895.
Caffeine’s ability to do this comes from the way it reacts with your central nervous system, heart and endocrine system. After you drink your caffeinated beverage or eat a food that contains caffeine, the chemical is very quickly transferred into your bloodstream and sent all around your body. The cognitive and physical effects of caffeine come from how it works its way into your central nervous system. Most notably, caffeine passes through a defensive layer in the brain called the blood-brain barrier (very easily), a region that protects the vital parts of the brain and nervous system from viruses or other invasive elements that enter our bodies. Caffeine actually has a very similar effect to many psychoactive drugs because it changes the way neurotransmitters (chemical messengers) in the brain operate. Caffeine changes the operation of neurotransmitters, especially with adenosine. Adenosine affects nearly every single system in the body by making us feel tired and sleepy. The chemical builds up during the day and it naturally binds to the receptors. As more adenosine binds to the receptors in our brains, we feel increasingly tired. Caffeine, however, can bind to the adenosine receptors without giving us that tired feeling, which is where caffeine earns its ability to wake us up. Caffeine has an additional effect on the production and transmission of dopamine, acetylcholine and serotonin. Dopamine is a chemical that boosts our mood and makes us feel happy. A similar reaction in the brain occurs when addictive drugs are consumed and caffeine is considered a narcotic. Increased levels of serotonin, like dopamine, lead to a feeling of happiness along with an increased feeling of alertness. Acetylcholine is linked to muscular activity, which leads to caffeine’s ability to remove physical fatigue, but it often leads to small tremors or the worsening of chronic shaking. Since all of the neurotransmitters in the brain are at heightened levels because of caffeine, this triggers the pituitary gland to secrete a hormone that stimulates the adrenal gland to produce cortisol and adrenaline (epinephrine). These chemicals produce an increased heart rate and other symptoms associated with the fight or flight neurological response.