Lots of folks ask whether Tagalog has snappy slang equivalents for 'nocturnal', and I find the mix of Tagalog, English, and Taglish really fun to watch. I notice that in everyday speech people rarely reach for a single native slang word that equals 'nocturnal'. Instead, we use phrases like 'gising sa gabi', 'aktibo sa gabi', or playful lines such as 'gabi ang peg' and 'gabi mode on'. For more formal talk you'll sometimes hear 'nokturnal' or 'nocturnal' borrowed straight from English, especially in medical or academic contexts.
If I’m out with friends late at night we throw around casual tags: 'night owl' (yes, in English), 'gabi-gabi ako', or 'gising pa rin'. Social media adds variants like 'gabi vibes' or 'gabi squad' that feel slangy and very contemporary. So no, there isn’t a single native slang synonym that’s dominant — instead there’s a whole palette of phrases and borrowings. I think that variety is kind of cool and says a lot about how adaptable Filipino language culture is, which I honestly enjoy watching unfold.