Here’s why. You may feel sleepy after drinking coffee because caffeine blocks adenosine receptors in the brain. Adenosine is an important brain chemical that impacts our sleep-wake cycles.

When caffeine blocks those adenosine receptors, something interesting happens. Your brain suddenly thinks the sleepiness signals have disappeared, even though the underlying tiredness hasn’t ...

The length of time caffeine stays in the body varies from person to person. Although it blocks adenosine receptors, it does not affect the production of new adenosine molecules. When caffeine ...

3 This increased adenosine concentration can affect caffeine's ability to block all the receptors, diminishing its effects. 3 Interestingly, studies have shown that the reduction in GABAergic ...

According to new research, having an afternoon cup of coffee might seem harmless—but caffeine continues to affect the body, ...

According to the American Medical Association, roughly 85% of Americans consume caffeine daily, yet most of us don’t think ...

SUNDAY, June 1, 2025 (HealthDay News) — Your morning cup of coffee might help you power through the day — but could it be keeping your brain too alert at night, even while you sleep?

Caffeine also blocks adenosine receptors. Adenosine is a molecule that helps regulate bodily functions like sleep, blood pressure, and heart rate—and when caffeine blocks these receptors ...

But when caffeine is present, it blocks adenosine by binding to receptors instead. In turn, this stimulates the release of neurotransmitters, thus increasing alertness, Rivkees said. Not everyone ...