What It Is
How It's Taken
Caffeine is ingested orally in the form of tablets, coffee, headache medicine, coffee, chocolate, coffee, tea, coffee, cola, coffee, caffeine powder, coffee, midol, and a whole bunch of other medications.
How It Works
Caffeine is a stimulant, I mentioned this already. It's also water-AND-fat-soluble (That alone should be proof that the gods want you to have it.) It acts as a competitive inhibitor to adenosine, a neurotransmitter believed to promote sleep (as the amount in your brain increases the longer you're awake, and it gets broken down when you sleep). When adenosine binds to an adensine receptor, it tells your body to slow down, when caffeine does it, things speed up instead. So you begin producing adrenaline, same as if you were being chased by a bear.
See, the Aracuan's all in there messing with your system because he got there first, and José Carioca's just standing there like " 'ey wait, what are you doin' up there? Craz' burd."
Caffeine's presence in the brain ALSO slows the reuptake of dopamine, so you feel happier... in the short-term, anyway. But that's not all, folks! That's right, boys and girls, caffeine's metabolites mess with you, too! See, when your liver breaks caffeine down, it creates paraxanthine, theobromine and theophylline. Paraxanthine goes to work breaking down fat and increases free fatty acids in your blood plasma, theobromine dilates your blood vessels and makes you need to pee, and theophylline relaxes smooth muscle. (Fun with the parasympathetic nervous system, this.)
- Increased short-term recall, and better memory later in life but the "correct" amount of caffeine to consume is difficult to determine, as caffeine can also depress the body's ability to grow new neurons (see below).
- Decreased risk of Parkinson's disease.
- Decreased risk of cardiovascular disease and diabetes. (PDF)
- Reduced risk of: Oral, esophageal and pharyngeal cancer for everybody, breast cancer in postmenopausal women, and may protect against liver cancer.
- Women who drink at least a cup of coffee a day decrease the risk and symptoms of depression.
- Decreased risk of boneitis.
Caffeine is toxic at large doses; the lethal amount estimated to be about 200mg/kg of body mass. (So if you're 160lbs, it would take about 101 cups of coffee to take you.) The risks are much higher for children, however, and there have been cases of young people, and those in weak health dying from their intake, but there are also cases where people just took dangerous amounts of caffeine. Death comes in the form of a V-fib. That is, your heart cannot contract properly, and blood flow stops.
There's also the risk of depressed neurogenesis, that is, a decrease in the brain's ability to grow new neurons, especially in the hippocampus. If neurogensis is significantly affected by caffeine consumption, then those consuming caffeine on a regular basis may find themselves with long-term memory difficulties, as well as trouble retaining new information. (General rule here: If you find yourself with any memory issues whatsoever, talk to a doctor asap.)
Intake has also been linked to an increased likelihood of sleep disturbance, anemia during pregnancy, and experiencing audio and visual hallucinations.
What fourth wall?
Caffeine withdrawal, should you decide to up-and-quit, results in the following (so brace yourself): headaches, fatigue, depression, decreased energy and alertness, difficulty concentrating, irritability, fogginess, nausea, vomiting and muscle pain and stiffness. You begin feeling crappy within about 12 hours, and peak unhappy-levels occur within 20 hours of stopping and can last up to nine days.
But I mean, that's all just, for high caffeine intake. Right?
What do you mean "Their baseline was 100mg/day before cessation"?
I mean, I'm totally ok. I just have a couple cups of coffee every day. That's no big deal, right?
Hey! Shut up! What would you know about it? I'll just keep tabs on how much I drink.
...Yeah. That's a good plan.