When this happens, the downstream sleep-promoting pathways aren’t activated, meaning you stay awake and alert in the meantime. Unless its receptors are blocked by caffeine, that is. After several hours of being awake, adenosine levels increase to a point where they start the process of making you sleepy. Its levels in your brain fluctuate - fairly low when you wake up and slowly building throughout the day. “It can do this because, structurally, caffeine looks very similar to adenosine, the molecule that usually binds to these receptors.”Īdenosine plays many roles, including helping to regulate your sleep/wake cycle.

“Caffeine works by blocking sleep-promoting receptors in your brain called adenosine receptors,” says Dr. It's here that caffeine elicits its most classic effect - helping keep you alert and awake. Once consumed, caffeine is very quickly absorbed and distributed throughout your body, including to your brain. So, when it comes to that gray area between late morning and early evening, how late is too late to drink that coffee you so desperately need - or even just a soda or iced tea with dinner - without it affecting your sleep? How does caffeine work? “Certain afternoon and evening habits can get in the way of that, and caffeinated beverages are one prominent example.” Rashad Ramkissoon, a primary-care physician at Houston Methodist. “It’s very important to be sure you’re getting quality sleep,” says Dr. (Right before bed, for instance.just in case.)īut is an afternoon pick-me-up really a problem? At the time, it felt like you needed it just as much as the sleep you're not getting now. You know caffeine can keep you awake, and there are the obvious times to avoid it. Or, maybe you're counting the number of hours you might get if you fell asleep right now. Specifically, the number of hours you're not getting. Instead of counting sheep you're counting hours of sleep.

Things that help you stay up