Two ways sleep reduces your risk of Alzheimer’s Disease

Sleep for brain health

Sleep helps your brain work better. Get enough good quality time between the sheets, and you’ll ace the competition in learning tasks, memory recall and reaction times. Recent research reveals the detrimental effect of chronic poor sleep in neurodegenerative conditions such as Alzheimer’s Disease ¹.

The link between insomnia and Alzheimer’s Disease

Alzheimer’s disease features progressive memory loss and may also include behavioural and mood changes as the disease progresses². Although the cause of Alzheimer’s disease is yet to be wholly understood, it is associated with abnormal deposits of amyloid beta and tau proteins in the brain. These two proteins are part of the healthy metabolic function of the brain ³. In Alzheimer’s disease, they cause problems when there is excessive production, decreased clearance or they change from soluble to insoluble forms.

Worldwide, Alzheimer’s Disease affects 10% of adults over 65 years old ⁴. Chronic insomnia and sleep apnoea present an increased risk for the development of this condition in otherwise healthy people. Conversely, once amyloid beta plaque deposits in the brain this also decreases restorative slow wave sleep and increases wakefulness creating a positive feedback loop that accelerates memory deterioration⁵. In mice models of Alzheimer’s Disease, 21 days of chronic sleep deprivation increased amyloid beta plaques by 200% ³. How this translates to humans is unknown, but the evidence suggests a significant role for sleep in reducing the risk of developing and also treating neurodegenerative conditions.

So how can sleep help?

1. Sleep clears up the brain garbage

The brain is very metabolically active, and all that work creates waste⁶. Like waste anywhere if the disposal system is inefficient you start getting blockages and things won’t work well. In the brain the garbage disposal system is called the glymphatic system. Recent research reveals this waste disposal system works more efficiently (possibly up to 80% better) when we are in slow wave sleep. The glial cells, which are a support cell for your nerves, shrink by about 60% allowing more cerebrospinal fluid to flow around your brain and flush out the wastes and toxins ^4,7. I liken this to garbage collectors finding it easier and more efficient to collect garbage while the city sleeps. Although it this early morning schedule doesn’t help my sleep!h

Body posture also influences glymphatic activity, and it is most efficient when sleeping on our right side as opposed to our backs. In animal models, this sleeping position places the heart at a higher position which helps the nervous system go into a relaxed (parasympathetic) state¹.

2. Melatonin is an antioxidant

In addition to being one of the essential hormones for sleep, melatonin is also a potent antioxidant and anti-inflammatory. Melatonin is beneficial in the brain because it inhibits the process that changes the insoluble amyloid beta molecule into a soluble plaque. Melatonin production increases up to 10 times at night, so sleeping well is going to make sure you have plenty of this floating around in your brain ².

While sleep is not the only contributing factor to the development of Alzheimer’s Disease it appears to play a significant role in reducing the risk of memory loss by ensuring your brain garbage is regularly cleared out. Now if only it could clear out all those lyrics 80’s pop songs that I really don’t need it my brain!

If you liked this, you might also enjoy

Why do I wake up early in the morning?

Sleep hygiene as a part of your everyday routine

References

1. Benveniste H, Lee H, Volkow ND. The Glymphatic Pathway : Waste Removal from the CNS via Cerebrospinal Fluid Transport. Neurosci. 2017;(February). doi:10.1177/1073858417691030.
2. Nesse RM, Finch CE, Nunn CL. Does selection for short sleep duration explain human vulnerability to Alzheimer ’ s disease ? Evol Med Public Heal. 2017;(September):39-46. doi:10.1093/emph/eow035.
3. Cedernaes J, Osorio RS, Varga AW, Kam K, Benedict C, Schi HB. Candidate mechanisms underlying the association between sleep-wake disruptions and Alzheimer ’ s disease. Sleep Med Rev. 2017;31:102-111. doi:10.1016/j.smrv.2016.02.002.
4. Mander BA, Winer J, Mander BA, Winer JR, Jagust WJ, Walker MP. Sleep : A Novel Mechanistic Pathway , Biomarker , and Treatment Target in the Pathology of Alzheimer ’ s Disease ? Trends Neurosci. 2016;(June). doi:10.1016/j.tins.2016.05.002.
5. Holtzman DM. EFFECTS OF DISRUPTED SLEEP ON ABETA AND TAU PATHOLOGY AND EFFECTS OF ABETA AND TAU PATHOLOGY ON SLEEP: A VICIOUS CYCLE? JALZ. 2015;11(7):P165-P166. doi:10.1016/j.jalz.2015.07.113.
6. Jessen NA, Sofie A, Munk F, Lundgaard I. The Glymphatic System – A beginner’s guide. Neurochem Res. 2015;40(12):2583-2599. doi:10.1007/s11064-015-1581-6.The.
7. Xie L, Kang H, Xu Q, et al. Sleep drives metabolic clearnance from the adult brain. Science (80- ). 2013;342(6156):1-11. doi:10.1126/science.1241224.Sleep.