Sleep
Why Sleep Matters for Healthy Aging
The dual power of preserving brain health and offering compensatory resilience.
Posted January 6, 2026 Reviewed by Margaret Foley
Key points
- Long-term poor sleep quantity and quality increases dementia risk by 10 to 20 percent.
- Sleep supports brain health by clearing waste and reducing inflammation.
- Sleep may help in maintaining thinking skills despite existing brain pathology by offering cognitive reserve.
- Cognitive reserve is the brain’s ability to adapt to damage to preserve cognitive performance.
By Dr. Zsofia Zavecz
People started living much longer over the last century, which raises an important question: How can we stay healthy and enjoy a good quality of life as we age? From a neuroscience perspective, this means keeping the brain healthy and working well for as long as possible.
As we get older, harmful substances and changes can build up in the brain. These changes can damage brain cells and cause the brain to shrink, a process called atrophy. We refer to these changes in general as brain pathologies. At the same time, thinking abilities, called cognitive functions, can also worsen with age. These include memory, attention, and problem-solving.
Poor brain health often leads to problems with thinking and memory and can eventually result in dementia. Research shows that sleep plays a role in this. Poor sleep over many years—whether because of a sleep disorder or simply not getting enough sleep (usually less than six hours a night)—can raise the risk of developing dementia by 10 to 20 percent (1,2).
The good news is that there are two ways we can protect brain and cognitive health. First, we can try to prevent harmful changes from building up in the brain. Second, we can support thinking skills even when brain damage is already present. This second approach is known as cognitive reserve and refers to factors that help people perform better than expected despite brain pathologies, by allowing the brain to work more efficiently or use alternative strategies.
Improving sleep is a great way to support both approaches. In the sections below, we explain how sleep helps protect the brain and how it may support thinking abilities despite existing brain damage, as well as simple steps anyone can take to benefit.
Sleep and brain health
Getting good sleep is linked to a slower buildup of harmful pathologies in the brain (3). Scientists are still learning exactly how this works, but we know that sleep supports many biological processes that help the body repair itself and fight off damage, including strengthening the immune system.
One process that has received a lot of attention in recent years is glymphatic clearance. During sleep, the brain becomes especially good at clearing out waste products that build up during the day when the brain is active. You can think of this like cleaning a dance floor: It is much harder to clean while the party is still going on, but much easier once most of the guests have left (Fig. 1).
Recent research also suggests that sleep may have an antioxidant effect, similar to the benefits of fruits and vegetables (4). This means that sleep helps reduce oxidative stress and inflammation, both of which can damage brain cells over time.
It’s likely that several of these processes work together during sleep to protect the brain.
Sleep as a cognitive reserve factor
The idea that sleep can help protect thinking abilities even when the brain already shows signs of damage is relatively new.
In a study published in 2023 (5), we found that better sleep was linked to improved memory performance the next day, but only in older adults who already showed signs of brain pathology. These individuals had amyloid‑beta (Aβ) plaques, early brain changes seen in Alzheimer’s disease. This suggests that good sleep may help support thinking abilities when these harmful brain changes are present.
You can think of it like this: Brain pathology pushes cognitive abilities downward, while sleep and other healthy lifestyle factors push them back up (Fig. 2). These factors don’t remove the pathology, but they help the brain cope and maintain better performance.
Because this research area is still developing, we need more studies to understand how long-term sleep quality affects cognitive resilience and whether sleep directly causes these benefits. Even so, focusing on changeable lifestyle factors like sleep to improve cognitive functions and quality of life is an exciting opportunity, especially since we currently cannot reverse severe brain pathology.
Sleep is a strong candidate for a cognitive reserve factor because people with more pathology may depend more on the biological processes supported by sleep, such as waste clearance and reduced inflammation, than people with healthier brains.
How to maximize the benefits of sleep
If you’re convinced that better sleep is worth the effort to protect brain and cognitive health, here are some simple steps that can help increase these benefits.
1. Address possible sleep disorders
The strongest evidence linking sleep and dementia shows that long‑term problems with sleep quantity and quality increase the risk of dementia. That’s why treating sleep disorders is one of the most important steps you can take. Snoring, for example, is often seen as harmless, but it is a sign of sleep‑disordered breathing. If you suspect a problem, consider getting tested at a sleep centre and exploring treatment options.
2. Keep a regular schedule
Our bodies follow a built‑in biological clock, called the circadian clock, which helps regulate sleep and wakefulness. As we age, this clock becomes less reliable, making it harder to fall asleep, stay asleep, or feel alert during the day. Keeping regular sleep and wake times, and mealtimes—even on weekends—helps support this system. Getting enough daylight, especially in the morning, and regular physical activity also strengthen daily rhythms.
3. Improve your sleep hygiene
Sleep hygiene refers to habits that support good-quality sleep. These include allowing enough time for sleep, keeping your bedroom dark, quiet, and cool (an eye mask and earplugs can help), and avoiding stimulants (like caffeine) and heavy meals close to bedtime.
4. Stay active during the day
Research shows that people tend to get more deep, restorative sleep when they are active during the day. Exercise, exploring new places, learning new skills, or spending time with others can all support better sleep. As a bonus, these activities also support brain and cognitive health on their own.
Closing thought
As we live longer, protecting brain health is important for maintaining independence and quality of life. Sleep is a modifiable factor that supports both brain health and thinking abilities, making it a key tool for healthy aging.
About the author: Dr. Zsofia Zavecz is a Lecturer in Cognitive Neuroscience in the School of Psychology at the University of Surrey.
References
1. Bubu, O. M., Brannick, M., Mortimer, J., Umasabor-Bubu, O., Sebastiao, Y. V., Wen, Y., ... & Anderson, W. M. (2017). Sleep, cognitive impairment, and Alzheimer’s disease: a systematic review and meta-analysis. Sleep, 40(1), zsw032.
2. Sabia, S., Fayosse, A., Dumurgier, J., van Hees, V. T., Paquet, C., Sommerlad, A., ... & Singh-Manoux, A. (2021). Association of sleep duration in middle and old age with incidence of dementia. Nature communications, 12(1), 2289.
3. Winer, J. R., Mander, B. A., Kumar, S., Reed, M., Baker, S. L., Jagust, W. J., & Walker, M. P. (2020). Sleep disturbance forecasts β-amyloid accumulation across subsequent years. Current Biology, 30(21), 4291-4298.
4. Vaccaro, A., Dor, Y. K., Nambara, K., Pollina, E. A., Lin, C., Greenberg, M. E., & Rogulja, D. (2020). Sleep loss can cause death through accumulation of reactive oxygen species in the gut. Cell, 181(6), 1307-1328.
5. Zavecz, Z., Shah, V. D., Murillo, O. G., Vallat, R., Mander, B. A., Winer, J. R., ... & Walker, M. P. (2023). NREM sleep as a novel protective cognitive reserve factor in the face of Alzheimer's disease pathology. BMC medicine, 21(1), 156.
