  About 90% of North Americans consume caffeine in some form every day, making it, along with alcohol and nicotine, the most popular drug in use. Caffeine comes in many foods, like coffee, tea, colas, energy drinks, and chocolate. Caffeine is a molecule called trimethylxanthine. In its pure form, it's a white crystalline powder that tastes very bitter. In medicine, caffeine is useful to stimulate the heart, and to increase urine production. When ingested in coffee, tea or chocolate, caffeine it is used to provide a 'boost of energy' or a heightened alertness, or sometimes to stay awake longer. Caffeine is an addictive drug. Its effects on the brain are similar to those of amphetamines and cocaine and heroin, except that caffeine's effects are milder. Here are some typical examples of the amount of caffeine in various food sources:
Many people consume 1000 mg or more of caffeine every day and don't even realize it. How Caffeine Affects Your Body: Adenosine is a chemical created in the brain; when it attaches to adenosine receptor cells, nerve cell activity in the brain slows down. This causes you to feel drowsy, and it also makes your blood vessels dilate (open wider) to allow more oxygen to reach the brain while you sleep. To a nerve cell, caffeine looks like adenosine! As a result, caffeine molecules can attach themselves to the adenosine receptor cells in your brain. The caffeine molecules don't slow down the nerve cells' activity like adenosine would, and they're blocking the receptor cells so that adenosine can't attach. The end result is that, instead of slowing down, the nerve cell impulses speed up. Caffeine also causes the brain's blood vessels to constrict, because it blocks adenosine's ability to open them up. This is why some headache medicines contain caffeine; if you have a headache caused by blood flow, the caffeine will narrow the blood vessels and help relieve it. Because of the increased nerve cell activity in the brain, the pituitary gland assumes there's some kind of emergency going on, so it releases hormones to make the adrenal glands produce adrenaline. Adrenaline has these effects on your body:
Caffeine also increases dopamine levels in the brain (amphetamines, as well as heroine and cocaine do this too, only much more so). Dopamine is a neurotransmitter that can activate the brain's pleasure center, making you feel good. This may be what leads to caffeine addiction. Once the adrenaline in your body dissipates, you will suffer from fatigue and depression. Many people combat this by reaching for another cup of coffee, to ingest more caffeine to get the adrenaline going again. But having your body in a continual 'state of emergency' like this isn't very healthy, never mind the fact that it makes you jumpy and irritable. Caffeine can have a drastic effect on how you sleep, since adenosine reception is important to deep sleep. It takes about six hours for half the caffeine you've ingested to disappear. That means that several big cups of coffee in the evening will keep caffeine in your body all night, preventing you from getting a good sleep. The next day you'll feel tired, so you'll need caffeine as soon as you get up. The addictive cycle starts all over again! When you attempt to break the caffeine addiction, you will become irritable, depressed, restless and tired, and you will get bad headaches for a few days as blood vessels in the brain open up again. But eventually your body will return to normal. |