this post was submitted on 17 Mar 2026
376 points (95.9% liked)

Comic Strips

22751 readers
2991 users here now

Comic Strips is a community for those who love comic stories.

The rules are simple:

Web of links

founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
[–] Duranie@leminal.space 3 points 3 hours ago

Correct - my best ELI5.

When you wake up your body starts producing adenosine, which slowly locks into receptors in your brain. As the day goes on, these receptors fill. By the end of the day your receptors are full which tells you you're tired and need to go to sleep. When you sleep, these receptors clear to start the next day fresh (which is one of the reasons if you don't sleep well, they don't all clear and you start the day tired.)

Caffeine fits these receptor sites, preventing the adenosine from locking in and delaying the onset of fatigue. Caffeine half life is about 5-6 hours, which can lead to the "crash" as the free adenosine starts locking into the receptors the caffeine is now making available as it breaks down.

When caffeine is consumed regularly and the brain isn't detecting the expected adenosine feedback, it responds by creating more receptors. More caffeine is now needed to account for the new receptors. If you skip caffeine with the addition of receptors, the adenosine fills the extra receptors faster and leaves you comparitively more fatigued/with withdrawal symptoms. If you reduce/abstain from caffeine for a few days the extra receptors are reduced and you return to baseline.