Better Deep Sleep May Delay or Prevent Alzheimer’s Disease

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How deep is your sleep?

Quality deep sleep may compensate for the cognitive dysfunction and memory impairment of Alzheimer’s disease and could become the target of future therapies, especially in early and mild cases of the disorder. That is the conclusion of a recent study investigating the relationship between sleep and Alzheimer’s. The finding offers a potential new weapon — a good night’s sleep — in the battle against what has become the sixth-leading cause of death in the United States, more lethal than prostate and breast cancers combined.

Alzheimer’s disease is a progressive, neurodegenerative disorder that leads to cognition impairment and irreversible memory loss. It is the most common form of dementia and afflicts about 10 percent of the population over age 65. Authors of a 2022 article in the journal Translational Psychiatry call Alzheimer’s one of the “most lethal, expensive, and burdening diseases in this century.”

The latest research was published in the June 2023 issue of BMC Medicine. In it, investigators write that “sleep may represent a novel modifiable [cognitive] reserve factor and thus a promising treatment target” for Alzheimer’s disease. Specifically, the team determined that sufficient amounts of quality deep sleep, defined as non-rapid eye movement (NREM) slow-wave sleep, support memory preservation and cognition, even in individuals with relatively high brain levels of the waste proteins beta-amyloid and tau, which are linked to Alzheimer’s disease. Study participants experiencing less deep sleep—or more disrupted sleep in general—had poorer cognition, even though the level of metabolic waste in their central nervous system was comparable to the higher functioning group.

If not flushed from the brain, beta-amyloids can begin to clump together, forming plaque—or, in the case of tau, neurofibrillary tangles—that impair communication among brain cells and lead to the eventual development of Alzheimer’s disease. Often, waste proteins start accumulating decades before symptoms of the disease become manifest.

About Deep Sleep

“Deep” is the stage of sleep when little, if any, dreaming occurs; heartbeat, respiration, and body temperature drop; muscles relax; cerebral blood volume falls; and electrical brain wave activity becomes slower and more rhythmic. During this phase, the body’s glymphatic system activates, allowing cerebral spinal fluid to enter the brain and cleanse it of waste materials, such as beta-amyloids. Deep sleep is what helps a person feel refreshed upon waking.

Research indicates that the pattern of brain waves during sleep is strongly associated with cognition. But, when deep sleep is insufficient due to sleep deprivation or a sleeping disorder like insomnia, a person’s risk for developing physical, neurological, and psychological problems such as depression, cancers, cognitive disorders, and even obesity, can increase markedly. A 2019 study in the journal Science showed that even a single night of sleep deprivation boosted levels of tau by as much as 50 percent in an otherwise healthy person’s cerebrospinal fluid.

More Research Needed

Of course, the relationship between sleep and Alzheimer’s disease remains complicated. It begs the question: Will effective treatment of sleep disorders or enhancement of time spent in deep sleep—when neuronal activity and metabolic waste production are at their lowest levels—reduce the incidence of Alzheimer’s disease, or slow its development, in any significant way?

Certainly more research is necessary. As the authors of a 2020 article in the Neurobiology of Disease journal ask:

• Do disrupted sleep patterns precede or result from the build-up of metabolic waste in the system?
• Which sleep disturbances most require treatment – insomnia, obstructed sleep apnea, uncontrolled leg movement disorder — and at what age should intervention begin?
• Will improvement in sleep actually decrease levels of waste proteins in cerebrospinal fluid?
• What specific physiological mechanisms or processes affect the association between Alzheimer’s and sleep?

What we do know is that scientific evidence supports the beneficial role of sleep in cognition and concentration, organizational skills, and executive decision-making; the preservation of memory; and the reduction – or prevention – of an onset of serious disorders, including Alzheimer’s disease and other types of dementia.

Sleep Essential Reads

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The Brain Benefits of Being a Night Owl (or a Drinker)

Getting Good Sleep

When is the best time to develop healthy sleeping habits? Now. Here are a few tips to help do that:

• Establish a regular routine of going to bed and arising at approximately the same time every day. Sleep loves rhythm.
• Allow a sufficient amount of time for sleeping. Experts recommend seven to eight hours of sleep daily for the average adult.
• Cut consumption of caffeine and alcohol several hours before retiring and eliminate computer and phone screen time at least an hour before retiring. Activity, caffeine, and alcohol will impair deep sleep.
• If possible, exercise daily, eat nutritiously, and skip late-evening meals. Leonardo da Vinci said, “A well-spent day brings happy sleep.”
• Avoid daytime napping.
• Find something relaxing to do shortly before bedtime: “Alexa, play me some soft mood music.”
• Keep the bedroom cool and dark. If you have a television in the bedroom, remove it. The bedroom is for sleeping, not for watching reruns of Friends.

And should you suffer from insomnia or another disorder that chronically interferes with sleep, seek appropriate treatment; do not rely on the hope that somehow the problem will magically disappear on its own.

For anyone with a family member affected by dementia, good sleep is the holy grail to improving cognitive performance. Speak with your doctor about medications and supplements that may improve sleep quality and depth, and be sure to check for sleep apnea, REM-behavior disorder, and restless-leg syndrome as well. All can be quite sleep disruptive, but all are readily treated.