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90% of Americans consume
caffeine in one form or another every day. More than half of all American adults
consume more than 300 milligrams (mg.) of caffeine every day, making it the most
popular drug by far. The caffeine comes in from things like coffee, tea, cola,
chocolate, etc.
Caffeine
is known as trimethylxanthine. When
isolated in pure form, caffeine is a white crystalline powder that tastes very
bitter. The chief source of pure caffeine is the process of decaffeinating
coffee and tea.
Medically,
caffeine is useful as a cardiac stimulant and also as a mild diuretic (it
increases urine production). Recreationally, it is used to provide a "boost
of energy" or a feeling of heightened alertness. It's often used to stay
awake longer. College students and
drivers use it to stay awake late into the night. Many people feel as though
they cannot function in the morning without a cup of coffee to provide caffeine
and the boost it gives them.
Caffeine
is an addictive drug. It operates using the same mechanisms that the
amphetamines, cocaine and heroin use to stimulate your brain. Caffeine's effects
are milder than amphetamines, cocaine and heroin, but it is manipulating the
same channels and that is what gives caffeine its addictive qualities. If you
feel like you cannot function without it and must consume it every day, then you
are addicted to caffeine.
Caffeine
occurs naturally in many plants, including coffee beans, tea leaves and cocoa
nuts. It is therefore found in a wide range of food products. Caffeine is added
artificially to many others, including a variety of beverages.
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Typical drip-brewed coffee
contains 100 mg per 6-ounce cup. Typical brewed tea contains 70 mg per
6-ounce cup.
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Typical colas (Coke, Pepsi,
Mountain Dew, etc.) contain 50 mg per 12-ounce can. Things like Jolt contain
70 mg per 12-ounce can.
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Typical milk chocolate
contains 6 mg per ounce.
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Anacin contains 32 mg per
tablet. No-doz contains 100 mg per tablet. Vivarin and Dexatrim contain 200
mg per tablet.
If
you sit down and calculate your caffeine consumption during a typical day, you
may be surprised! You may consume a gram or more every single day and don't even
realize it.
As
adenosine is created in the brain, it binds to adenosine receptors. The binding
of adenosine causes drowsiness by slowing down nerve cell activity. In the
brain, adenosine binding also causes blood vessels to dilate (presumably to let
more oxygen in during sleep).
To
a nerve cell, caffeine looks like adenosine. Caffeine therefore binds to the
adenosine receptor. However, it doesn't slow down the cell's activity like
adenosine would. So the cell cannot see adenosine anymore because caffeine is
taking up all the receptors adenosine binds to. So instead of slowing down
because of the adenosine level, the cells speed up. You can see that caffeine
also causes the brain's blood vessels to constrict, because it blocks
adenosine's ability to open them up. This effect is why some headache medicines
like Anacin contain caffeine. If
you have a vascular headache, the caffeine will close down the blood vessels and
relieve it.
So
now you have increased neuron firing in the brain. The pituitary gland sees all
of the activity and thinks some sort of emergency must be occurring, so it
releases hormones that tell the adrenal glands to produce adrenaline
(epinephrine). Adrenaline is, the fight or flight hormone and it has a number of
effects on your body:
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Your pupils dilate
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Your breathing tubes
open up (this is why people suffering from. severe asthma attacks are
sometimes injected with epinephrine)
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Your heart beats faster
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Blood vessels on the
surface constrict to slow blood flow from cuts and also to increase blood
flow to muscles. Blood pressure rises.
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Blood flow to the
stomach slows
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The liver releases
sugar into the bloodstream for extra energy
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Muscles tighten up
ready for action
This explains why, after drinking a big cup of coffee, your
hands get cold, your muscles tense up, you feel excited and you can feel your
heart beat increasing.
Caffeine
also increases dopamine levels in the same way amphetamines do. Dopamine is a
neurotransmitter that, in certain parts of your brain, activates the pleasure
center. Obviously caffeine's effect is much lower than heroin's, but it is the
same mechanism. It is suspected that the dopamine connection contributes to
caffeine addiction.
So
you can see why your body might like caffeine in the short term, especially if
you are low on sleep and need to remain active. Caffeine blocks adenosine
reception so you feel alert. It injects adrenaline into the system to give you a
boost. And it manipulates dopamine production to make you feel good.
The
problem with caffeine is the longer-term effects, which tend to spiral. Once the
adrenaline wears off you face fatigue and depression. So what are you going to
do? You take more caffeine to get the adrenaline going again. As you might
imagine, having your body in a state of emergency all day long isn't very
healthy, and it also makes you jumpy and irritable.
The
most important long-term problem is the effect that caffeine has on
sleep.
Adenosine reception is important to sleep, and especially to deep sleep. The
half-life of caffeine in your body is about 6 hours. That means that if you
consume a big cup of coffee with 200 mg of caffeine in it at 3:00 PM, then by
9:00 PM about 100 mg of that caffeine is still in your system. You may be able
to fall asleep, but your body probably will miss out on the benefits of deep
sleep. That deficit adds up fast. The next day you feel worse, so you need
caffeine as soon as you get out of bed. The cycle continues day after day.
This
is why 90% of Americans consume caffeine every day. Once you get in the cycle,
you have to keep taking the drug. Even worse, if you try to stop taking
caffeine, you get very tired and depressed and you get a terrible, splitting
headache as blood vessels in your brain dilate. These negative effects force you
to run back to caffeine even if you want to stop.
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