How does caffeine make you more alert and work as a cognitive enhancer if it reduces blood flow to the brain?

Question

I’ve just read that a 250mg dose of caffeine can reduce blood flow to the brain by 22%-30%.

It seems counter intuitive to me that a chemical that restricts blood flow to the organ responsible for all mental operations actually improves our mental functioning.

There’s probably a simple answer but 22-30% seems like it would significantly impair the brain’s functioning

In: 129

Answer 1

Throughout the day, we get tired and build up adenosine. Think of adenosine as bricks in a rucksack. As you’re awake longer, your adenosine rucksack gets heavier and you get more tired.
Caffeine is an adenosine antagonist, or stops it from working. Therefore, it removes adenosine bricks from your rucksack. Thus, as the rucksack is lighter, you’re less tired.