The Spanish stay up late. It can be "very early" at almost any time of night.
A co-worker from Madrid called Seville a "pueblo," culturally backward, when we couldn't find a drink at 5:30 in the morning.
We did find one place, though. Somebody told us about it as he was having us leave his bar at about 3:30. It's up around the corner, he said turn left and then another left. Up a narrow road and then another. We found a closed door. Eugenia pressed a buzzer.
The barman let us in, and served us beer. I felt slightly uncomfortable, since I didn't want us to keep him from going home. We were the only ones there.
A large dog traipsed in a lugubrious fashion behind and in front of the bar.
Not knowing the culture and not speaking Spanish well, I assumed of course that the barman was just finishing the his cleanup (the place was spotless,) and that he was being kind enough to let us have a last beer.
But another patron showed up, joined in conversation, got a beer... and then another... and more people.... The place was just opening.
Bar El Mundo, nearby Plaza Alfalfa. Opens at 3:30. At that hour, the night is young.
I lived in Seville from December 2000 until June 2001.