A cup of brewed coffee has about 110 milligrams of caffeine, and potent as it may seem an espresso about 80mg. But of course that's based on volume; 8 ounces for a cup of coffee and 1.5 oz for espresso. Drip coffee has about 13mg/oz., espresso has a whopping 51mg/oz, and instant decaf only has .31mg/oz.
A can of Coca-Cola has about 23mg of caffeine, Pepsi Cola 25mg, Mountain Dew 37mg, and TAB 31mg.
A cup of tea has about 40mg of caffeine, while an ounce of chocolate contains about 20mg.
This all comes up because I'd had a hard time concentrating lately. I'd be jumping from webpage to webpage, back to email, over to Flickr, back to email, check out the news, and and and . . . .
Decided to cut out caffeine (about 8 cups a day), and boy did I find out what cold turkey means. By the end of the first day and all through the second I had a headache that Tylenol couldn't cure. Second night, third day, and third night I had legs that ached as if I'd run 10 miles. By day four I felt human. Yup, all known symptoms of caffeine withdrawal.
Recounting the ordeal to a friend he told me that when he was in the Army he drank so much cofee that he had withdrawl symptoms on weekends. Couldn't figure out why by Sunday afternoon he was a wreck. Flight Surgeon told him it was coffee. Sure 'nuff.
Use of caffeine apparently goes back to stone Age, and coffee dates back to 9th century Ethiopia, although it was banned in 12th century Turkey. Nevertheless, coffee is the most widely used psychoactive stimulant in the world, and 90% of Americans use the drug everyday.
Not trying to make a point here, but it is one of those things that made me say, "Wow! Really?"
This is what caffeine does to a spider: