Have you always done that sleep-in-two-stages thing?
Not always, though as a child I did occasionally wake up in the middle of the night and
stay awake for what seemed to me like a fairly long time. Tonight I went to bed too early
and since I don't usually sleep many hours straight through, now I am awake at 1:52 a.m.
It's possible that my Strattera causes this too, it does seem to make me sleep less deeply.