The relationship between sleep and dementia is complicated. Although sleep disturbances have been tied to dementia and cognitive decline in older individuals, a causal link between sleep and dementia has not been shown.
Does poor sleep put people at higher risk for dementia? Or does dementia contribute to poor sleep quality? Maybe both.
In this blog, we will explore the relationship between sleep and dementia, discuss whether improving sleep could reduce dementia risk, and provide suggestions for how to sleep better.
How does sleep quality affect dementia?
A hallmark sign of dementia is an accumulation of beta-amyloid protein in the brain. Beta-amyloid is a type of protein fragment in the brain. Many researchers believe that the build up of beta-amyloid in the brain, and the damages it causes to brain cells, contributes to impairments in individuals’ ability to think, remember and function independently.
Dr. Adam Spira1 and colleagues from The Johns Hopkins University conducted a sleep study of seventy older adults and found that shorter sleep duration and poor sleep quality are associated with increased beta-amyloid accumulation. It was unclear from the study, though, which came first: elevated beta-amyloid or poor sleep.
In order to better understand the link between sleep and beta-amyloid, Dr. Ehsan Shokri-Kojori2 from the National Institutes of Health (NIH) measured twenty participants’ brains after getting a full night’s sleep and after a night of sleep deprivation. He found that beta-amyloid increased about 5% after participants lost a night of sleep. This result further contributes to the evidence that sleep quality and duration can impact beta amyloid levels.
Can good sleep help reduce dementia risks?
Both animal and human studies have shown that beta-amyloid level increases during wakefulness and decreases during sleep. This suggests that sleep functions like a “janitor” cleaning out waste products in the brain. During the day, the brain produces some beta-amyloid protein, and during the night, good sleep can remove beta-amyloid accumulated during the day.
Tips to sleep better
Keep a consistent sleep schedule by going to bed and waking up at the same time every day.
Keep it a little chilly in your bedroom. The brain receives signals to sleep when your core body temperature drops.
Avoid using a computer, smartphone, or TV in the last hour before bed.
Make sure to get some physical exercise during the day, but avoid exercising close to bedtime.
A short nap might enhance the quality of your nighttime sleep but a late and long afternoon nap can make it more difficult to get to sleep at night.
If you’re having trouble falling asleep, get out of bed and engage in a soothing activity outside of your bedroom, like reading in low light. Only go back to bed once you feel sleepy.
For More Information
References
Spira, A. P., Gamaldo, A. A., An, Y., Wu, M. N., Simonsick, E. M., Bilgel, M., … & Resnick, S. M. (2013). Self-reported sleep and β-amyloid deposition in community-dwelling older adults. JAMA neurology, 70(12), 1537-1543.
Shokri-Kojori, E., Wang, G. J., Wiers, C. E., Demiral, S. B., Guo, M., Kim, S. W., … & Volkow, N. D. (2018). β-Amyloid accumulation in the human brain after one night of sleep deprivation. Proceedings of the National Academy of Sciences, 115(17), 4483-4488.
Kang, J. E., Lim, M. M., Bateman, R. J., Lee, J. J., Smyth, L. P., Cirrito, J. R., … & Holtzman, D. M. (2009). Amyloid-β dynamics are regulated by orexin and the sleep-wake cycle. Science, 326(5955), 1005-1007.
Vanderheyden, W. M., Lim, M. M., Musiek, E. S., & Gerstner, J. R. (2018). Alzheimer’s Disease and Sleep–Wake Disturbances: Amyloid, Astrocytes, and Animal Models. Journal of Neuroscience, 38(12), 2901-2910.
