I started reading a very good book, Why We Sleep by Matthew Walker. It states that the caffeine in coffee operates by clogging up the receptors of adenosine, which accumulates throughout the day and contributes to sleep pressure—the growing urge to sleep. However, what the book doesn’t mention, and what I’m curious about, is why people drink coffee in the morning when there is minimal adenosine in the body to begin with. Well, theoretically, caffeine could linger for several hours, but usually, adenosine doesn’t build up enough within a few hours to cause drowsiness.
Interestingly, in the evening or at night, coffee works—but as they say, there’s a catch. Caffeine temporarily blocks the adenosine receptors, making you feel alert. Yet, adenosine continues to accumulate in the background, and by nighttime, there’s a ton of it. As soon as the caffeine level drops, all the accumulated adenosine molecules “crash onto the receptors. This causes a sharp wave of sleepiness and fatigue—and that’s the infamous “crash.
Is there an explanation for morning coffee? Or is it just tradition?
Hi, I'm Rauf Aliev. 