Low fiber high saturated fat and sugar diets are associated with lighter, less restorative, and more disruptive nighttime sleep.
A fascinating study showed that, "During sleep, the flow of cerebrospinal fluid in the brain increases dramatically, washing away harmful waste proteins that build up between brain cells during waking hours."
Dr. Maiken Nedergaard, a professor of neurosurgery at the University of Rochester, along with a team of scientists, discovered this "washing away" process when they studied the brains of mice that were sleeping. Dr. Nedergaard states that the scientists noted that during sleep, cerebrospinal fluid circulated through the brain and nervous system at a "very rapid pace." They believed this to be partly due to the brain cells of the mice actually shrinking when they fell asleep, making it easier for the cerebrospinal fluid to circulate. She goes on to say, "The process is important because what's getting washed away during sleep are waste proteins that are toxic to brain cells. This could explain why we don't think clearly after a sleepless night and why a prolonged lack of sleep can actually kill an animal or a person."