Caffeine blocks adenosine receptors, which build sleep pressure, leading to a 'caffeine crash' when receptors are flooded.

“Caffeine acts as an adenosine antagonist, what that means is that when you ingest caffeine, whether or not it's coffee or soda or tea, or in any other form, it binds to the adenosine receptor, it sort of parks there just like a car would park in a given parking slot, and therefore, adenosine can't park in that slot.”

“The most common one is of course caffeine which if you watch the sleep episodes, you know reduces this molecule that makes us sleepy called adenosine.”

“Caffeine is in a class of drugs that we call the psychoactive stimulants. So it works through a variety of mechanisms, one is a dopamine mechanism dopamine we often think of as a reward chemical or, but dopamine is also very much an alerting neurochemical, as well. But its principal mode of action, we believe in terms of making me more alert and keeping me awake throughout the day is on the effects of adenosine.”

“The way that caffeine works is that it comes in, competes with quite sharp elbows with adenosine competitively forces them out of the way, hijacks that receptor by latching onto it, but then just essentially blocks it.”

“Caffeine essentially acts to block the effects of adenosine. It's a competing agonist, not to get technical, but it binds to the receptor for adenosine for some period of time and prevents adenosine from having its normal pattern of action. And thereby reduces our feelings of fatigue.”

“So caffeine really hits these three systems. It hits other systems too, but it mainly reduces fatigue by reducing adenosine, increases alertness by increasing epinephrine release, or adrenaline release I should say, both from the adrenals in your body and form locus coeruleus from within the brain. And it can, in parallel to all that, increase the action or the efficacy of the action of dopamine.”

“When you drink caffeine, it's going to increase your levels of adrenaline and so-called epinephrine, which will increase your energy levels. It's going to decrease levels of something called adenosine, which builds up while you're sleepy. It's going to make you feel less sleepy, more alert, more energetic.”

“Caffeine effectively operates as a adenosine antagonist. It works by basically occupying the receptor for adenosine. So it's a little bit of a convoluted mechanism. But basically all you need to know is that caffeine prevents the actions of adenosine. That's one of the reasons why caffeine makes us feel alert.”

“its ability to offset the sleepiness system, if you will, this adenosine system, and to control our schedules in that way to essentially take a withdrawal against the bank that is adenosine and then pay that back later in the form of getting sleepy later as opposed to when we want to be alert”

“caffeine acts as an adenosine antagonist. It reduces your feelings of lethargy and fatigue and your desire to sleep by parking in the receptors for adenosine and not allowing adenosine to have its pro-sleepy, if you will, effects on your brain and body.”

“Caffeine will competitively bind to those receptors therefore that's why caffeine stops you from feeling like you want to go to sleep”

“caffeine works on those same receptors that doesn't make sense caffeine if it's working on those same receptors should increase your sleepiness it doesn't because it when it binds onto those adenosine receptors those welcome sites in the brain it simply blocks them it doesn't deactivate them nor does it activate them it simply blocks them”

“Caffeine acts as an adenosine antagonist. What that means is that when you ingest caffeine, whether or not it's coffee or soda or tea or in any other form, it binds to the adenosine receptor. It sort of parks there just like a car would park in a given parking slot. And therefore adenosine can't park in that slot. Now, when caffeine parks in the adenosine receptor slot, nothing really happens downstream of that receptor. The receptor can't engage the normal cellular functions of making that cell and you feel sleepy. So the reason caffeine wakes you up is because it blocks the sleepiness receptor. It blocks the sleepy signal.”

“However, caffeine is an adenosine blocker. It's actually a competitive antagonist for you aicionados. sort of parks in the receptor that adenosine normally would park at and prevents adenosine from acting on that receptor. That's why you feel more alert.”

“and that's also why caffeine is problematic right so caffeine blocks adenosine receptors so that's that you know the caffeine crash when it wears off and then all the adenosine floods The receptors and we experience that oh sleepiness right”

“Caffeine works by blocking adenosine, a molecule that builds up the longer you’re awake and makes you feel tired.”

“caffeine is binding to adenosine receptors and essentially, you know, blunting the effect of adenosine, any adenosine that's still left over in the morning from binding to those receptors and causing you to feel sleepy. And it's one of the reasons why you get that acute alertness effect from drinking caffeine because you're not then feeling that effect of adenosine. um the impact of adenosine binding to those receptors.”

“Caffeine blocks these receptors, essentially removing that break, allowing the brain circuits associated with alertness and attention, you know, powered by neurotransmitters like dopamine and norepinephrine and acetylcholine to become more active.”