We routinely monitor blood pressure, cholesterol, blood sugar, and heart health as we age. But there is another vital sign of long-term health that deserves just as much attention:
How well are you sleeping?
Sleep isn't simply the time when your brain turns off. In many ways, it's when some of the brain's most important maintenance work begins.
Your Brain Has a Nightly Cleanup System
Throughout the day, billions of brain cells are constantly working. Like every active system in the body, that activity produces metabolic waste that needs to be cleared.
During sleep, the brain's glymphatic system helps move fluid through brain tissue and remove metabolic waste. Research increasingly suggests that this process is particularly active during non-REM sleep and slow-wave activity, the brain activity associated with deep sleep.
Among the substances being cleared are amyloid-beta and tau, proteins closely associated with Alzheimer's disease when they accumulate abnormally in the brain.
A 2026 randomized crossover study in 39 adults provided especially interesting evidence. Researchers compared normal overnight sleep with sleep deprivation and found evidence consistent with greater overnight clearance of amyloid-beta and tau from the brain into the bloodstream during normal sleep. Greater non-REM sleep duration and EEG delta activity were among the physiological factors associated with greater clearance. The findings support a role for sleep in brain maintenance, but do not establish that improving sleep prevents Alzheimer's disease.
Think of sleep as part of the brain's nightly maintenance cycle.
You wouldn't want to run an important piece of machinery continuously without giving it time for maintenance. Your brain also needs periods of restoration.
Deep Sleep Matters
Not every stage of sleep performs exactly the same job.
Deep, slow-wave sleep is characterized by large, slow electrical waves in the brain. This stage has important roles in restoration, memory, and brain physiology, and growing research connects slow-wave activity with glymphatic function and amyloid biology.
This becomes especially important as we age because deep sleep commonly becomes shorter and more fragmented. Older adults tend to experience lighter sleep, awaken more frequently, and spend less time in some sleep stages.
That doesn't mean the aging brain no longer needs sleep.
It means getting healthy sleep can become more difficult at exactly the time we should be paying close attention to it.
The Myth: “Older People Don't Need as Much Sleep”
I hear this frequently.
“I'm getting older. I guess I just don't need as much sleep anymore.”
That isn't what current recommendations say.
According to the National Institute on Aging, older adults generally still need about seven to nine hours of sleep each night, similar to other adults. What changes with age is often our ability to get good-quality sleep, not the importance of sleep itself.
Insomnia becomes more common. Sleep apnea becomes more common. Pain, medications, medical conditions, nighttime urination, changes in circadian rhythms, and other factors can repeatedly interrupt sleep.
So when an older adult sleeps five or six fragmented hours every night, we shouldn't automatically dismiss it as:
“That's just aging.”
It may be something worth investigating.
Sleep and the Aging Brain
The relationship between sleep and brain aging appears to go in both directions.
Poor sleep has been associated with cognitive problems and Alzheimer's-related pathology, while changes occurring in the aging or diseased brain can themselves interfere with normal sleep. Researchers are still determining exactly how these relationships interact over decades.
We cannot yet say that improving sleep prevents Alzheimer's disease. The National Institute on Aging describes the relationship as an active area of research, including whether treating poor sleep might help delay or prevent cognitive decline.
But that uncertainty shouldn't make us ignore sleep.
Sleep affects memory, attention, emotional regulation, cardiovascular health, metabolism, immune function, and the brain's ability to restore itself. Adequate sleep remains important throughout later life.
Don't Just Ask How Long You Slept
Seven hours in bed doesn't necessarily mean seven hours of restorative sleep.
I want to know:
Are you reaching deep sleep?
Is your sleep fragmented?
Are you waking repeatedly?
Are you snoring or potentially experiencing sleep apnea?
Do you wake feeling restored?
Are you sleepy during the day?
Has your sleep changed significantly from five or ten years ago?
These questions become increasingly important as we age.
If you're consistently sleeping poorly, don't simply accept it as normal aging. Talk with your physician or a sleep specialist and determine why.
Sleep Should Be Part of Every Brain-Health Plan
People spend enormous amounts of money trying to protect their brains as they age: supplements, exercise programs, special diets, cognitive-training programs, and brain-training technologies.
These approaches have different levels of evidence and may have a place depending on the person. But none should cause us to overlook one of the most fundamental biological processes the brain performs every night.
Sleep is brain maintenance.
And deep, restorative sleep appears to be particularly important to the physiological processes that help maintain a healthy brain environment.
We can't control every factor that determines how our brains age. Genetics, cardiovascular health, metabolic health, inflammation, environmental exposures, disease, physical activity, nutrition, social connection, and many other factors contribute.
But sleep is something we can pay attention to.
Don't wait until memory begins declining to start thinking about the quality of your sleep.
If we want healthier brains at 70, 80, and 90, protecting sleep needs to become part of the plan decades earlier.
Because getting older doesn't mean your brain needs less sleep.
It may mean that protecting the sleep you get matters more than ever.
Sources and Further Reading
Dagum P, et al. (2026). The glymphatic system clears amyloid beta and tau from brain to plasma in humans. Nature Communications, 17, 715.
National Institute on Aging. Sleep and Older Adults.
National Institute on Aging. Does poor sleep raise risk for Alzheimer's disease?