A writer for Yahoo News explores the science behind why caffeine can make some people feel tired.

When caffeine hits our brain,  Michelle Worley, a registered nurse and Director of Clinical Operations at Aeroflow Healthcare explains, it adheres to your brain’s adenosine receptors. Adenosine is what helps us feel sleepy. So, when caffeine binds to those adenosine receptors, it stops our brain from feeling tired. But—there’s a twist! “Just because our brain is no longer processing the adenosine doesn’t mean it stops producing it. When the caffeine inevitably wears off, you’re left with an adenosine buildup which makes you feel even more tired.”

Get the full story at yahoo.com.