It has been long held that sleep facilitates memory consolidation. Nevertheless, could sleep play an even more important role in brain detoxification?
A new animal mice study recently found awake versus unconscious sleep states resulted in a physiologically different brain. During sleep the space between brain cells increased by 60 percent. This interstitial space is called the glymphatic system. During sleep, cerebrospinal fluids flushed out the neural-toxic wastes, such as beta-amyloids, that accumulated during the day. This change in the physiological state resulted in a quicker clearance of waste products from mouse brains.[Xie 2013]
The human brain suprisingly due to its high metabolic rate lacks lymphatic circulation. Instead, it has its own private waste disposal system called the glymphatic system. The cerebrospinal fluid is theorized to serve a lymphatic function. Due to the larger size of the human brain, the role played by the glymphatic system may be even more critical than it is for rodents.[Iliff 2012]
There is, of course, the blood-brain barrier whose role is restricting access to the brain. Hence, the existence of the brain's separate glymphatic system in many ways is to be expected.
Furthermore, beta-amyloids that have been implicated as a causative factor of Alzheimer’s and other degenerative brain diseases were found to accumulate in the mice's brains when they were deprived of sleep. Levels of beta-amyloid have been a focus of the growing scientific literature on biomarkers for dementia for a long time. Furthermore, most interventions currently under investigation for Alzheimer’s disease focus on manipulating beta-amyloid levels.[Koyama 2012]
Sleep Detoxifies Your Brain
The downside to this research is that it has yet to have been proved to occur in human beings. Further brain imaging studies in humans will be needed to confirm this theory. Nevertheless, accepting such a theory provides a natural health strategy for avoiding getting Alzheimer’s disease during old age. Furthermore, a sleep driven metabolite clearance of brains theory makes a lot of sense. Since most vertebrate animals do sleep, this feature of brain health probably evolved millions of years ago. Brains have evolved to maximize brainpower with very limited space and resources.
“The brain only 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... We need sleep. It cleans up the brain.”
-- Maiken Nedergaard, researcher
While science is immortal, people are NOT. Consequently, we have to proceed with limited information, until a better approach becomes available. The implication of this study is that sleep therapy could be used as a practical natural health strategy to avoid getting age-related dementia.