Having read quite a bit of brain science -- and quite a bit about those different parts of the brain that have to work together -- I can understand how a person could have a 'divided mind'. My mind is less divided than most, more singleminded -- except for sometimes when I'm asleep. See, I have generally a very responsible mind when asleep. My sleeping mind isn't obsessive like my waking mind, and it tends to avoid topics that might upset me. And my sleeping mind occasionally seems to know far more than my waking mind -- it knows things I honestly don't know how it knows -- and I have a habit of listening to it and taking its messages quite seriously.
Occasionally, though, when I've had the wrong thing to eat before bed, or when something is physically wrong, my mind can get a little hyper... and then it wants to explore/ try out negative possibilities. What if... it asks. Ah, but then another part of my sleep brain is like... Uh oh, oh boy, we can't have this! And that second part goes around trying to clean up the mess. (Think of Sleeping Beauty, where the banished fairy says the princess will prick her finger and die, but then another fairy says oh no, she won't die, she'll just sleep for a hundred years.)
