Finally! Scientists Discover Why We Need Sleep
Scientists have known for centuries that sleep is essential to human health. Deprive some poor sap, human or animal, of sleep over enough nights and he becomes depressed and delusional and suffers seizures.
Keep it up… and he dies.
But why? What, exactly, sickens and then kills the sleep-deprived? Or to put a different spin on it, what is it about getting optimal sleep that makes and keeps us healthy?
Intriguing research on mice from a team at the University of Rochester Medical Center in New York and recently published in Science1 suggests the answer.
Just as fire creates ash, every organ in the body creates waste products as part of its daily energy consumption.
For every organ but the brain, the lymphatic system continually sends its cleansing fluids gushing through the spaces between the cells, washing this debris into the bloodstream, which takes it to the liver for recycling.
But the brain is different. Though its high metabolic rate means it burns even “hotter” than other organs, it does not have a conventional lymphatic system. Instead, the researchers found that the brain has its own special power-washing process.
Special cells called astrocytes form a network of channels around the brain’s arteries and veins. The cleaning process uses these in a three-step sequence:
1. Cerebrospinal fluid (CSF) gushes into the brain in these channels around the arteries.
2. The fluid washes through brain tissues and mixes with the waste-filled fluid that surrounds the cells of the brain.
3. Finally, the CSF collects in the channels around the veins. It drains out of the skull back toward the liver, taking the waste with it.
Here’s where sleep plays its vital role.
During sleep, the brain’s cells actually shrink, boosting the spaces between cells by an incredible 60 percent. This boosts the efficiency of the three-step cleaning process immensely, as these wide-open spaces allow waste products to be cleared much more effectively.
Proteins linked to neurodegenerative diseases, including one called beta-amyloid, are among the waste products this process clears. A thick, sludge-like buildup of beta-amyloid around brain tissue is a hallmark of Alzheimer’s disease.
Now, it’s a bit early to form solid conclusions about what this means in terms of lifestyle changes that can lower Alzheimer’s risk. But combining this result with other Alzheimer’s research, here are three that seem likely to help:
- Eat fewer carbohydrates — especially sugar — as these have been shown to boost beta-amyloid production, perhaps overwhelming the natural clearing process
- Stay hydrated. All of the body’s waste disposal processes work best if the waste-transporting fluids between cells — which are mostly water — can flow in optimal quantities
- Get enough sleep! The sleep need not happen in a continuous block, as long as the total volume in a 24-hour cycle is enough to make you feel refreshed and raring to go.
Personally, I find this information extremely powerful.
As a hardheaded science guy, the command “You need to sleep, but no one knows why” has never struck me as compelling.
But “You need to sleep or your brain will clog with toxic byproducts, promoting dementia and early death” grabs my attention.
I hate, however, to conclude this on a negative. So let’s focus on the positive flip side.
A well-rested brain is a clean brain, and “clean” means quick, responsive, agile, and durable. Like a high-performance engine right after an oil change, a brain freshly and efficiently washed overnight is not only ready for the day’s race — it starts a lap ahead of the pack.
Sincerely,
Doug Hill
Director, Laissez Faire Club
Citations
1Xie, Lulu et al. “Sleep Drives Metabolite Clearance from the Adult Brain.” Science (New York, N.Y.) 342.6156 (2013): 10.1126/science.1241224. PMC. Web. 20 May 2015.
