‘The Why’ of Sleep

If there is a word that personifies modern life, it would be: ‘busy’. Busy is something we pride ourselves on; no matter the arena. To be the first to arrive at work, and the last to leave, is glorified. A mum who manages to hold the family together, while doing all the home-life stuff, including multiple extra-curricular activities for the kids, while putting herself last, is said to be exhausted a ‘Super-Mum’; doubly so if she is single. The cost, that is almost always paid for busyness, is sleep.

On a deep level, we know that sleep is the ultimate expression of rest and recovery; and we are tired. So why don’t we sleep more?

I can almost hear the psychological defences mounting; the excuses; the justifications; the rationalisations. What it all comes down to, though, is this: we don’t prioritise sleep; because we’re busy.

‘I’ll sleep when I’m dead.’

An all too poignant quote, as opting out of sleep, will make you dead; literally.

We have long-known that no sleep can lead to myriad of serious health conditions and studies have shown that between 11-32 days of no sleep may even kill you1. What we didn’t know is why, but a recent discovery brings new knowledge to light. Bear with me and I’ll get to it, there are just a few things you need to understand first.

The human body possesses a series of blood vessels that are like water pipes; they carry good stuff around the body. In parallel to the vascular system, is the lesser-known lymphatic system; a system of sewerage pipes – if you like – that transport waste. The human brain makes up around 2% of our total body weight2, and yet is responsible for roughly 60% of glucose usage in a resting state3. Interestingly, despite being so much more metabolically active than any other area of the body, the brain does not have a lymphatic system.

How is it that our most vital of organs generates so much metabolic waste, and yet has no system to remove it? The answer, of course, is that it does; the previously elusive, and yet elegant ‘glymphatic system’.

While you sleep, your neurons compress in on themselves, like sponges, to squeeze metabolic and other toxins into a newly created paracellular space in between the now shrunken spongey neurons. This specific function occurs almost exclusively while you sleep.

Said another way: sleep is when your brain detoxes. No sleep means no removal of metabolic gunk. A critical build-up of neuronal waste can result in death4.

Sleep is important.

Most people don’t die for lack of sleep, but these things are never as simple as black and white. 28 hours or more of no sleep results in a cognitive impairment to the equivalent of a Blood Alcohol Concentration of 0.10%5. Just a week of less than six hours of sleep a night, results in the same cognitive impairment.

Said another way: when you skip out on sleep, despite thinking that you are operating fine, your brain is gunked-up to the point where you cognitively function as if you are drunk; just without the fun ‘buzz’.

Probably at times you have skipped out on sleep, and your own personal experience suggests that after a few days of extra sleep you are back to normal. We can ‘catch up’ on sleep… right? Well yes, and no… maybe. On this, I have no studies to support my thinking, intuitively compelling as it may be.

If an accumulation of waste in your brain is what causes under-functioning, then with extra sleep, you should be able to work through a ‘back-log’, clear it all, and hence have reset your brain and ‘caught up’. My suspicion, however, is that you will never completely ‘catch up’ on the neuronal damage already sustained through increased time in contact with metabolic and other waste.

While you can perhaps prohibit further damage by ‘catching up’, you can’t entirely undo damage already done. We know that there are elements of health that can be brought back into alignment with extra sleep like cortisol, daytime sleepiness and fatigue, but there are certainly critical elements of health which cannot be improved by playing catch up, including performance deficits6.

The physical restorative effects of sleep are well understood, as is the role of memory consolidation. Suboptimal sleep has been linked with type 2 diabetesweight gain, hypertension and cardiac events7, just to name a few.

We, of the modern world, like to burn the candle at both ends; soon enough we must pay the piper. I believe that busyness, and the resulting: stress, lack of sleep, poor food habits, and inattention to diet, are the root of modern chronic disease. Don’t make the mistake of thinking you can achieve your optimal health by paying attention only to the ‘doing’ things, like diet and exercise.

This is your wake-up call. Get your full sleep quota.

 

 

 

References

131: Everson CA, Bergmann BM, Rechtschaffen A. Sleep deprivation in the rat: III.
2 Marcus E. Raichle,  10237–10239, doi: 10.1073/pnas.172399499
Berg JM, Tymoczko JL, Stryer L. Biochemistry. 5th edition. New York: W H Freeman; 2002. Section 30.2, Each Organ Has a Unique Metabolic Profile. Available from: https://www.ncbi.nlm.nih.gov/books/NBK22436/
4 RAS-MAPK-MSK1 pathway modulates ataxin 1 protein levels and toxicity in SCA1. Park J, Al-Ramahi I, Tan Q, Mollema N, Diaz-Garcia JR, Gallego-Flores T, Lu HC, Lagalwar S, Duvick L, Kang H, Lee Y, Jafar-Nejad P, Sayegh LS, Richman R, Liu X, Gao Y, Shaw CA, Arthur JS, Orr HT, Westbrook TF, Botas J, Zoghbi HY. Nature. 2013 May 29.

https://directorsblog.nih.gov/2013/06/04/protein-pile-up-common-cause-of-brain-disease/

Williamson, A., & Feyer, A. (2000). Moderate sleep deprivation produces impairments in cognitive and motor performance equivalent to legally prescribed levels of alcohol intoxication. Occupational and Environmental Medicine57(10), 649–655. http://doi.org/10.1136/oem.57.10.649
Total sleep deprivation. Sleep. 1989 Feb;12(1):13-21. PubMed PMID: 2928622.
6 Am J Physiol Endocrinol Metab. 2013 Oct 1;305(7):E890-6. doi: 10.1152/ajpendo.00301.2013. Epub 2013 Aug 13. Effects of recovery sleep after one work week of mild sleep restriction on interleukin-6 and cortisol secretion and daytime sleepiness and performance.
7  Nagai, M., Hoshide, S., & Kario, K. (2010). Sleep Duration as a Risk Factor for Cardiovascular Disease- a Review of the Recent Literature. Current Cardiology Reviews6(1), 54–61. http://doi.org/10.2174/157340310790231635 

2 thoughts on “‘The Why’ of Sleep”

  1. Hi Matt and thanks for taking the time to comment on this post. Yes the brain’s lymphatic system is fascinating and we speak to that in the followup blog on The Way of Sleep. I agree, we’re learning more and more and it’s wonderful. Bee

Comments are closed.

Scroll to Top