Ever wonder why you’re always reading about how important sleep quality is -- not just quantity? Well, modern science still doesn’t know all of the molecular mechanisms behind why we need sleep. As of last month, we now know more.
A new study, published in Science in October and entitled “Sleep Drives Metabolite Clearance from the Adult Brain,” finds just that: we need to sleep specifically so that the brain can focus on cleaning itself out each night.
Lead study author Dr. Maiken Nedergaard summarizes in a statement: “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.”
The study’s abstract states:
We here report that sleep has a critical function in ensuring metabolic homeostasis. Using real-time assessments of tetramethylammonium diffusion and two-photon imaging in live mice, we show that natural sleep or anesthesia are associated with a 60% increase in the interstitial space, resulting in a striking increase in convective exchange of cerebrospinal fluid with interstitial fluid. In turn, convective fluxes of interstitial fluid increased the rate of ?-amyloid clearance during sleep. Thus, the restorative function of sleep may be a consequence of the enhanced removal of potentially neurotoxic waste products that accumulate in the awake central nervous system.
While you rest, your brain is busy sweeping the floor, washing the dishes, and taking out the trash to prepare itself for the next day.
Your Glymphatic System: The Good Kind of “Brain Drain”
You probably haven’t read much about the glymphatic system because it hasn’t hit the mainstream, but you will.
In 2012, researchers identified this new maintenance system called the glymphatic system, which uses the cells’ mitochondria to remove cellular waste from the brain. It found that the clear cerebrospinal fluid (CSF) in the brain is what is responsible for draining toxins from the brain, much like how the lymph system in other organs is what removes waste from those cells to the kidney and liver. But the brain has no lymph – it has CSF instead.
The scientists noted that this system is particularly active during sleep. In other words, as you sleep your brain cells’ mitochondria remove cellular waste.
Things you can do during the waking hours that may positively influence the way cerebral spinal fluid (CSF) enters the brain’s glymphatic system later when you sleep:
Yoga and movement (especially inversions)
Standing instead of sitting at your desk which may move more CSF
Pranayama and just about any other breathing exercices
Massage and chiropractic care