Sleep is Your Brain on Detox

January 06, 2014
Sleep is Brain Detox
Reference:  Science Oct 2013

If you don’t get enough sleep, how do you feel?  Lousy.  Cranky, irritable, can’t remember….to name a few of the consequences of inadequate sleep.  We know sleep appears to consolidate memory, but it might do something else even more important: detox.  That’s what this article suggests.

The brain is an incredibly active organ, using at least 20% of our energy while only having 1% of our weight.  That means the cells are really humming.  They are delicate little devils, using up to 50 different neurotransmitters and connecting to each other with over 100 trillion connections.  Each neuron is shrink-wrapped with glial cells to protect it from outside poisons and toxins.  Those glial cells are essentially white cells and therefore part of our immune system.   We do know that the sleeping brain uses just as much energy as the awake brain, so sleep is not resting for the brain.  It has to be something else.

 But what is that something else?  We still aren’t sure, but we are sure we need it. To get a hint of what’s happening , Dr Nedergard did a very unique experiment.  Using double photon imaging, he was able to tract a dye injected into the fluid system in which the brain floats in mice.   He was able to show that the spaces between the brain cells increased by as much as 60% when the mice were asleep. The lymph fluid between the cells started flowing much faster.  The brain cells shrank down.

 Dr Nedergard has been on a bit of a role. Last year she reported that the fluid around the brain dumps into the lymph system of the body (the fluid that accumulates between your tissues and flows through your lymph glands and then into your venous circulation.)  She called it the glymphatic system (great pictures and explanation of U of Rochester web site).   She was curious to fully understand this system and what role it played in wakefulness and sleep. When the sleeping mice were awakened, the flow slowed down dramatically and the cells reinflated up to their full size quite promptly.  

They were also able to show that the protein beta-amyloid gets cleared out of the brain at twice the rate during sleep than while awake.  Beta-amyloid is what accumulates in the damaged Alzheimer’s brain.  It is considered a neurotoxin that is naturally made, but needs to be disposed of promptly.  Well, sleeping does that. Different animals need different amounts of sleep.  We humans become almost dysfunctional if we are awake more than 18 hours.  By 24 hours, we are in crisis mode and can fall asleep very easily.  

Eight hours seems to suit us. Cats need 12 hours. Dogs sleep as much as 16 hours a day.  Elephants only sleep 3 hours.  Is that because their brain is that much bigger and can accommodate space for the detox to be happening all the time?

 WWW.  What will work for me?  Hmm.  No wonder I feel so good when I get a full 8 hours.  Or why it is so delicious to fall asleep on Sunday afternoon and get “trapped inside a nap”, unable to emerge from my delicious slumber.  My brain is telling me it needs clean up its act.  Maybe I’ll make more of an effort to get my full 8.

 Pop Quiz

 1.  Your brain uses sleep to help consolidate memory?  T or F                      Answer:  Yup. That was our first understanding of sleep.
 2.  Your brain rests while your sleep and uses less energy, allowing you to awaken and feel refreshed?  T or F                     Answer:  Nope.  You must have been texting while reading.  You burn as much energy while asleep as while awake.  Consider the weight-loss implications.
 3.   Our brains have a drainage system here-to-for undiscovered that connects to every brain cell and allows it to drain off toxins.  T or F                       Answer:  True.    
4.   If you are the researcher that discovers it, you get to name it, and Dr Nedergaard called it the "glymphatic" system.  T or F                       Answer:   True.  Crafty name as it describes it well: a combination of glial cells working with the lymphatic system to get rid of gunk.
 5.   During sleep, the glymphatic system swells by about 60% and flows as much at two times faster.  T or F                     Answer:   True - Bingo
 6.   During sleep, your brain can get rid of beta-amyloid twice as fast as while awake.  T or F.  Answer:     True
 7.  You need more sleep.  T or F                   Answer:  True.  Americans are averaging under 7 hours a night.  Not good.

Column written by Dr. John Whitcomb, MD at Brookfield Longevity, Brookfield, Wisconsin.