.....at nearly 2am?
For me, it's insomnia. Although technically can it be called insomnia when I only ever got about 4 hours sleep even when I slept "normally"?
The wee hours are when I get my best editing done, transcribe a few songs (since I can hardly practice at 2am in a terraced house) and watch B movies whilst pondering how they ever got the finance to get made.