Yeah really no need to study this. There's "anecdotal" and then there's "this happens to 80% of people and we have cute euphemisms for when you excuse yourself" and that to me is as good as the most rigorous of studies. Now uhh, excuse me, back in a sec.

Chiming in for n+1. Can confirm: I enjoy my post-caffeine quiet time. :)

Hmmm, I smell an IG Nobel prize opportunity for an ambitious grad student who is not afraid to get his hands dirty.

What? I drink rather a lot of coffee and have never had that effect. I've never heard it from anyone else either. Is there any non-anecdotal evidence for this?

Do you primarily drink iced, cold brewed, or something like keurig?

Nope, just normal coffee. Sometimes made in a cafetiere, sometimes from the (rather good) machine at work, but I mostly make Greek or Turkish style these days. It's never given me a dose of the shits however its made though!

The caffeine relaxes the intestinal tract..