Essentially: electrical stimulation of the brain can cause some to wake up, and some to enter a state between awake and asleep; sounds fairly intuitive. I have

Essentially: electrical stimulation of the brain can cause some to wake up, and some to enter a state between awake and asleep; sounds fairly intuitive. I have had personal experience of lucid dreams, when I was very young I would stare at my bedroom wall until I fell asleep, the concentration must have kept me awake to some degree.