Why does your brain shrink when you're asleep?

September 25, 2017

I recently listened to an outstanding presentation delivered by Dr John Roberts on migraines and pain related issues from a Dental Perspective. One of the things that Dr Roberts touched on was the importance of sleep from a neurobiological perspective. What he mentioned was another piece of puzzle, that fitted into the bigger picture of great health and prevention of dis-ease.



We all know what it feels like when we don't get enough sleep...


Have you ever experienced time where you just couldn't sleep properly? Too much going on, busy mind, stress... Or you worked on your laptop too long, leaving you wide awake. Or you were travelling and sleeping in a bed that wasn't that comfy, Although this happens to me very rarely, when it does, oh boy, what a grumpy bugger I become! I don't feel myself, I have no drive to be productive, my patience and tolerance levels go way down and I'm far from sociable.  Having my seven to eight hours a day of great uninterrupted sleep are essential to me. And I guess this might be the case for you too! 


Now I can imagine that some of you may be in a stressful job or an environment where the lack of sleep becomes a norm. And I hear you. It's difficult sometimes and I'm not here to preach. But here's something essential for you to know that might lead you to reflect on your current situation and your health priorities for now and for the future.



The neurobiological perspective of sleep

Neurobiology studies the biology of the nervous system, including the brain. There's a large number of processes that go on during sleep in our brain. Our memory is consolidated, information is processed and stored, cells are maintained and repaired. Our brain is a super intelligent self regulating system created to perfection. 


Our body as an energy factory


We all know the idea behind a car running on petrol or diesel. We fill up the tank with petrol, we run the engine, waste products are excreted into the open space and the fuel's eventually used up as we use its energy to drive us to places. We also know that if we run an engine in an enclosed space (a garage), the carbon monoxide (CO) starts to accumulate and eventually we die of CO poisoning.


The same process happens with our cells. We eat food, we drink water, we breath. Instead of petrol we use on ATP (adenosine triphosphate), produced in the cell factory called mitochondria.The waste products created throughout are transported away, processed further and eventually excreted from our body (think wee and poo).


Now picture the brain. The brain and its activity is fueled by the astounding 1/4 of the whole energy supply, although the percentage of the body's mass the brain takes up is only 2%. So how has the Nature's elegant design solved the process of fueling it and removing wastes at the same time from this ingenious body part?


The Glymphatic System: the brain's own waste maintenance plant 


Throughout the whole body, the specifically designed Lymphatic system takes on the role of waste removal. Interestingly, that's not the case for the head, which leads to the next question: What is the brain's solution to the problem of waste clearance?


We call it the Glymphatic system (glia + lymph) and the main player here is the cerebral spinal fluid (CSF) and the glial cells (the cushioning of brain cells called neurons).


Potentially neurotoxic waste produced by the brain cells is ingeniously collected by the the CSF which flows through the glial cells, This makes the CSF not only the brain's shock absorber but also  a transporter of nutrients, chemicals filtered from the blood and wastes products from the brain.


Why does the brain shrink while we're asleep?


What do you think is the perfect time the intelligence of Nature has chosen for the brain to run the process of waste clearing? 


Neuroimaging done as part of a research project answered this question. It was discovered that the key period when the CSF is most active (increasing by the astonishing 95%), 'flushing' the brain and the nervous system, is during sleep. Our brain cells shrink by 60% allowing the brain space to be filled with the CSF.


So when we're thinking, working, playing and getting on with our day (whilst doing more thinking) our brains are putting off their clearing mechanisms to help us function at optimal level. When we're asleep, however, is when all the brain's own daily spring clean begins.


Research also suggests that there' may be some implications of these findings relative to the development of some of the neurodegenerative diseases  such as Alzheimer's.


Keep your house clean.


The fact is, that if you don't clean your house or maintain your kitchen, if you don't do the dishes, clean your bathroom or take the rubbish out, your environment becomes very unpleasant to live in (to say at least). So if you're not getting enough good quality sleep or are thinking that you can simply exist and go on like this, now is the best time to reconsider. Perhaps looking for sustainable and holistic solutions to help you improve your sleep patterns and keep your house clean and tidy is a good start.



University of Rochester - Sleep Drives Metabolite Clearance from the Adult Brain (3:20s)


The Glymphatic System Animation (0:53 s)


Neuroscience & Sleep: The Glymphatic System (6:11 s)



One more reason to get a good night’s sleep | Jeff Iliff (TEDx Talk - 11:45s)






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