Either woken up late, or you were awake and just stayed in bed. But, yes.

It means you're still awake, late at night. You haven't gone to bed yet. "You're up early" means you're awake early in the morning. "You wake up late" means exactly that.

Ta mate! :)

It means you have stayed awake until late or you have been up a long time ie. On the computer late at night someone may say 'you're up late' If you stay in bed late in the morning that would be 'a lie in' or 'I woke up late'

Peachey is on the money!