Well . . . I've been up since 4 am . . . and think I've unravelled the mystery . . . at 4:15 this morning my BGL was 4.6 (83). Obviously nothing wrong with that, but if I'd gone back to bed and slept for another 3 hours, I bet it would have bottomed out and then been high again (I know, just the liver doing it's job too well as usual

).
So now my day is all out of balance -- it's only 6:45 and I've already had breakfast. Anyway . . . guess I'll go back to bed for a bit.