Wasn't on Route 9 but this caught my attention because something similar happened to me on the A47 out near Swaffham about two years back. Left a mates house at half 10, got home and it was nearly 1am. Journey should've taken 40 minutes max. No memory of stopping, no explanation. I just sort of... came back to myself on a straight stretch of road about 5 miles from home.
The frustrating thing is nobody ever takes these seriously unless they've had it happen to them. It's not like falling asleep at the wheel, it doesn't feel like that at all. There's a quality to it that's hard to describe, like the journey just got edited out.
Would really like to hear more details from OP - was there anything in the sky before it happened, any weird feeling beforehand like pressure in your ears or a feeling of being watched? Those details matter. The time loss on its own could be anything but the context usually points somewhere more interesting.