This was actually pretty new info to me until about a year ago, that tea contained caffeine just as coffee does, and more per dry weight than coffee, but significantly less when infused (after adding hot water). If you’re the average American then coffee is a large part of daily life (I mean just look at the easily available cup from the Starbucks around the corner). Disputably, around the world, after water of course, either tea, coffee, or beer are the most consumed beverages in the world. I for one, believe its tea as its served in most restaurants on the Asian continent not to mention the bubble tea boom in many countries. But, because caffeine is such a big thing required for people to have the energy to get through the day, most people would forget that its still a psychoactive drug (drugs that change the personality of the user). Caffeine is the main constituent in coffee and tea, along some other lesser compounds but its main job is as a stimulant for the CNS (central nervous system). Shortly after consuming caffeine, it gets your blood level to peak in less than an  hour.

The chemical makeup of it is similar to adenosine to the right, as you can probably infer. Caffeine acts as a competitive substrate, it tricks the body into thinking that its adenosine instead, and adenosine’s job is to slow down neural activity and cause drowsiness. Caffeine stops the sleepiness thats usually caused by adenosine by binding to the receptor sites that adenosine was supposed to bind to. So instead of neuron activity decreasing and blood vessels dilating due to natural adenosine, the opposite will occur and there is increased activity. Feedback of this is given to the pituitary gland, which mistakes the body’s reaction for being in danger, thus it release hormones that produce epinephrine (adrenaline) causing a heightened state of alertness. Caffeine also inhibits some enzyme actions, and this extends the effects of the epinephrine. Hence we get the boost we need throughout the day from consuming either coffee or tea, although coffee is much more effective containing more caffeine per cup.

Caffeine has a half life of ~6hours varying with the individual’s metabolism (rate that the body performs chemical reactions) and other factors. For example, say you drink a few cups in the morning as part of your routine, ~270 mg of caffeine, after the day 12 hours, you still have ~67.5mg of caffeine in you, before you go to bed hence its good to think about when you drink your tea/coffee, depending also, on how fast your body processes it and if you’ve gotten used to its effects.


How much caffeine in your cup also varies by cultivation and infusion, etc… but roughly this is how it goes:

keep in mind that caffeine’s 1/2 life is ~6hours.

The more oxidized the tea is, the more caffeine the brewed tea has.

Approx caffeine content for common beverages:

brewed coffee                      135mg/8oz.

decaffeinated coffee          5mg/80z.

espresso                                 125mg/1.25oz. (1 shot)

white tea                                15mg/8oz.

green tea                                20mg/8oz.

oolong tea                              45mg/8oz.

black tea                                 70mg/8oz.

decaffeinated tea                 2mg/8oz.

soda                                           35-55mg/12oz.