How Exactly Does Caffeine Deliver Its Energizing Effects? Experts Explain

Caffeine is one of those things that just makes life easier—especially on days when you can't seem to snap out of a funk or the morning after a work deadline, a noisy neighbor upstairs, or a little one who needs some love keeps you up until the late hours of the night.

There's a lot of hubbub about caffeine (globally and especially in the U.S.), but how much do we actually know about this phytonutrient and how the unique plant compound works? What is that alertness we feel after consuming a cup of coffee? Is it actually energy, or is there more to the story here? Well, we've asked some experts, and they have the answers. 

Some claim that caffeine doesn't give you energy, it just makes you forget that you're tired. So, what's the deal with this minor distinction? Well, it seems to be mostly semantic. Nonetheless, this distinction and difference may speak to our misunderstanding of exactly how caffeine interacts with our physiological systems (and how it's seemingly been energizing the human race for, well, thousands of years). 

So if the "energy" we feel from caffeine doesn't come from fuel molecules or ATP, how do its effects on the central nervous system support that energizing feeling that our coffee or tea (so lovingly) offers us?

"[Caffeine] reduces the activity of a neurotransmitter called adenosine, which is responsible for putting the brakes on other neurotransmitters that have an excitatory or stimulant effect. The net effect is increased stimulation,"* shares Johnson.

Essentially, adenosine builds up as you're awake and attaches to its receptors on brain cells later in the day (and through the night) to slow them down, making you feel sleepy. Caffeine competes with the latter from happening by taking adenosine's place and binding to its receptors2. 

This antagonistic interaction with adenosine receptors also allows for the release of excitatory neurotransmitters—such as glutamate, norepinephrine, acetylcholine, dopamine, and adrenaline—by blocking inhibitory chemicals, Crouch adds. 

Unfortunately, at some point, that caffeine will give way to adenosine and—*crash,* you've hit that dreaded the 3 p.m. slump. But as Ferira alluded to before, that slump scenario is, of course, if you're relying solely on instant-release caffeine rather than a strategic mixture of instant- and sustained-release caffeine sources. Such a combo can thankfully be found in innovative supplements, like mbg's focus+.

While caffeine doesn't give you energy in the traditional (food equals ATP) sense of the word, there's no doubt that it makes you feel more alert and energized.* 

"Indeed, research outcomes including increased alertness3, concentration4, productivity, mood balance5, and even creativity6 (so cool!) are clearly and repeatedly borne out in the published science for caffeine thanks to its adenosine-dampening actions,"* concludes Ferira.

And according to Johnson, the benefits of caffeine—which include powerful mental stimulation, feeling more wakeful and alert, and even enhanced athletic performance—are best experienced when it's consumed at "judiciously chosen times."* 

Plus, we can't forget that some sources of caffeine (e.g., whole coffee fruit7, i.e., the coffee "berry" or "cherry," interchangeable terms) offer a healthy dose of polyphenolic antioxidants and promote oxidative balance throughout the body.* 

And as it turns out, "caffeine itself has antioxidant properties8, so while it might be famous for energizing us daily, it's not all about energy. This is a truly fascinating plant compound,"* shares Ferira.

So, whether you define energy as feeling more alert or prefer its more technical nutrition definition of fueling molecules and cellular pathways with ATP, caffeine can be an effective way to deal with our often demanding world. And like anything else, caffeine balance is critical—not too much, not too often, and always paired with some actual energy in the form of calories from nutrient-dense food.