Logically, the caffeine should be earning its keep in helping Daniel stay awake.

Logically, he should recognize that inebriated crashing on someone's couch might send all sorts of messages he's not sure Seth wants him to be sending.

Logically, he should be getting up and trying to forestall the alcohol-induced drowsiness that's starting to make this couch feel like an excellent place to simply lose all consciousness for a while.

Daniel supposes alcohol has a way of nullifying logic. Or he would suppose as such if he weren't in the process of passing out on Seth's couch.

Which is exactly what he's doing, despite himself.