Oh, Brenda, I know what you mean about tooling along in a familiar area with your mind otherwise occupied and realized you can't recall the past few blocks or where you were going. Good comparison! And sleepwalking has to be so much more frightening.
I've only had a brush with it myself. My daughter did some sleepwalking as a young child. The alarm on the house gave her away, or we might not have caught her before she went outdoors. It was scary!
Thanks everyone for your comments! It's so true, there is a lot of good in both city and small town living. Some of my character have real issues with not having the anonymity of the city.