I once did a motorcycle trip across Canada when I was young, poor, and eager to ride motorcycles. One night my plan was to make it to my friend's place in Montreal, but it got late and I was still in Ontario. Ontario is long. It's not easy to appreciate how long Ontario is. It was dark and I was tired, but I wasn't seeing any campgrounds and didn't want to spend money on a motel. So I kept pushing, as one does at that age, thinking I'd simply will myself to stay awake.
Suddenly I startled awake with the awareness that I had fallen asleep and had been riding while asleep (presumably just for a second or two). What shocked me awake was realizing that these lines of Coleridge's poem had been playing in my head:
Softly and smoothly went the ship,
Moved onward from beneath.