"I've always envied people who sleep easily. Their brains must be cleaner, the floorboards of the skull well swept, all the little monsters closed up in a steamer trunk at the foot of the bed."
When David Benioff wrote those words in his 2008 novel "City of Thieves," he probably didn't know how close he was to literal truth.
In a report released earlier this week, researchers from the University of Rochester Medical Center for Translational Neuromedicine found that sleep plays an even more important role in our mental health and well-being than heretofore has been realized.
The title of the study, which was published in Science, really does reveal all: "Garbage Truck of the Brain."
"This study shows that the brain has different functional states when asleep and when awake," said Dr. Maiken Nedergaard, co-director of the URMC Center and lead author of the report. "In fact, the restorative nature of sleep appears to be the result of the active clearance of the by-products of neural activity that accumulate during wakefulness."
During our waking hours, our brains are under attack by enormous amounts of sensory data -- scents, tastes, language, touch, the written word, etc. -- all which must be processed, analyzed, utilized, stored away for later use or discarded.
Yes, our brains are amazing but all that sensory input is hard work for an organ that weighs a mere three pounds on average.
During waking activity, the brain produces waste products that are stored between the cells and while we sleep, the brain's "garbage truck," dubbed the glymphatic system, using cerebral spinal fluid flushes the brain of that waste, which has been linked to Alzheimer's disease and other neurological disorders.
"Mental illnesses, such as Alzheimer's disease and dementia, are thought to occur because of a buildup of beta-amyloid plaque and tau-based neurofibrillary tangles, two biomarkers whose direct mechanisms for causing diseases are unknown, yet which are routinely suspected in leading to such diseases," wrote Chris Weller for Medical Daily. "Scientists from the University of Rochester Medical Center now argue in their latest study, published in Science, that sleep serves as a means to export cerebral waste before either biomarker has the chance to accumulate."
Weller noted that for the longest time, it's been a commonly accepted theory that sleep is nothing more than "an evolutionary mistake."
"Humans are at their most vulnerable when they sleep, so it makes little sense that prehistoric humans, without the modern comforts of home alarms and under-the-pillow revolvers, would voluntarily become unconscious while the sun is on the other side of the earth."
But Nedergaard said the brain has limited energy at its disposal, "And it appears that it must choose between two different functional states -- awake and aware or asleep and cleaning up. You can think of it like having a house party. You can either entertain the guests or clean up the house, but you can't really do both at the same time."
Researchers around the world are intrigued by the study results and wonder how it might apply to treating neurodegenerative diseases, because those who have trouble sleeping, have insomnia or get by only a few hours of sleep can experience a build-up of waste products, resulting in brain disorders.
"These findings have significant implications for treating ‘dirty brain' disease like Alzheimer's," Nedergaard said. "Understanding precisely how and when the brain activates the glymphatic system and clears waste is a critical first step in efforts to potentially modulate this system and make it work more efficiently.
While this is another step toward understanding the brain's functions and treating neurodegenerative diseases, treating sleep disorders has been another tough nut to crack for scientists.
This is because there are a number of factors that contribute to a good night's sleep, including multiple neurotransmitters such as serotonin, dopamine and norepinephirne, stress, exercise, diet, cardiac health and substance abuse.
So this new study is good news because it reaffirms the pivotal role sleep plays in our lives, but it's just another baby step toward helping those with sleep disorders or neurodegenerative diseases. For many of us, the result of this latest study is good news, but it still doesn't mean a full night of restful sleep. And for those of us with family or friends with Alzheimer's or dementia, it's small relief, but hope in a seemingly hopeless world.