Want to Improve Your Memory? Do This at Night…

Imagine waking up feeling foggy, forgetting simple details, or struggling to recall a familiar name. Now, imagine that these moments aren’t just occasional lapses but signs of something more concerning—your brain’s health at risk. Recent research suggests that the key to preserving your memory and protecting yourself from dementia may be simpler than you think: getting the right amount of sleep. But how much sleep is enough, and could too little—or even too much—be putting your cognitive future in jeopardy?

Key Takeaways

• Sleep Duration Matters – Sleeping fewer than six hours per night is associated with increased amyloid beta levels in the brain, a key marker linked to Alzheimer’s disease.

• Too Much Sleep Isn’t Ideal Either – While oversleeping (nine or more hours) didn’t show the same amyloid buildup, it was linked to reduced executive function, higher BMI, and more depressive symptoms.

• Quality Sleep Preserves Cognitive Function – Maintaining a consistent seven to eight hours of sleep per night is crucial for memory retention, cognitive health, and reducing dementia risk as you age.

Too Much Sleep or Too Little? The Truth About Brain Health and Aging

One of the easiest and most important things you can do to improve your memory and protect against dementia is to go to bed at a regular time every night and sleep well. If you’re a long-time reader of this newsletter, then you’ve likely heard me tout the memory benefits of sleep many times before. Now, a recent study reveals another reason why sleep is so critical to memory and, even more important, how much sleep you need.

Psychologists at the University of California, Berkeley, recently studied sleep habits about maintaining a healthy brain as you age. The research team found that poor sleep is linked to changes in the brain that are connected to the development of Alzheimer’s disease. For example, they found that people who report a declining quality of sleep as they age from their 50s to their 60s have more amyloid beta protein tangles in their brains, putting them at higher risk of developing Alzheimer’s disease. “Insufficient sleep across the lifespan is significantly predictive of your development of Alzheimer’s disease pathology in the brain,” said the study’s senior author, Matthew Walker, a sleep researcher and professor of psychology.¹

Another group of researchers, led by Joe Winer, a postdoctoral research fellow at Stanford University in California, is teasing out even more details about the link between sleep and cognitive health. It seems when it comes to sleep, there’s a sweet spot. Too little is detrimental, but so is too much. Mr. Winer’s new study, published in the journal JAMA Neurology, begs the question…

How Much Sleep is Enough?

The authors of this new study understood that disrupted sleep is common in later years. And when sleep changes occur, so do changes to cognitive function -- the mental capacity for learning, thinking, reasoning, problem-solving, decision-making, remembering and paying attention can all become negatively affected.³ Equally important, the researchers knew that age-related changes in sleep have been linked to early signs of Alzheimer’s disease.⁴ The researchers wanted to investigate possible links between self-reported sleep duration, demographic and lifestyle factors, subjective and objective cognitive function, as well as participants' levels of beta amyloid proteins. The team found that both ends of the sleep duration spectrum could have varying effects on older adults’ brain health.

Sweet Spot for Sleep

Those in the study who operated on a sleep deficit – six hours or less – had elevated levels of amyloid beta. Mr. Winer explains that amyloid beta "greatly increases" risk for dementia. (There is research that questions the link between amyloid beta and Alzheimer’s disease—more on this in a minute— although this is still the accepted belief in the medical community.) Mr. Winer and his team compared this group of short sleepers to participants who reported normal sleep patterns, which the researchers defined as seven to eight hours of sleep per night.

What did they learn?

The older adults with insufficient sleep performed moderately to significantly worse on tests commonly used for assessing cognitive abilities, memory, language, visual-spatial skills; and identifying mild dementia.

And what about those snoozers who reported sleeping nine or more hours a night? Researchers said that while this group did display lesser executive function, they did not have elevated amyloid beta levels.

Make Time for Sleep

"The main takeaway is that it is important to maintain healthy sleep late in life," Mr. Winer said. "Additionally, both people who get too little sleep and people who get too much sleep had higher (body-mass index and) more depressive symptoms."

He added that the findings suggested that both short and long-duration sleep might involve different underlying disease processes. However, the presence of amyloid beta (amyloid-β) is of utmost concern. "Amyloid-β is one of the first detectable markers in the progression of Alzheimer's disease," Mr. Winer explains. "In Alzheimer's disease, amyloid-β proteins start to build up throughout the brain, sticking together in plaques. Amyloid plaques are more likely to appear as we age, and many people with amyloid built up in their brains remain healthy.”

He notes that about 30 percent of healthy 70-year-olds will have substantial amounts of amyloid plaques in their brain. Not only do many healthy adults have high levels of the plaques, but many people with dementia don’t have them. What’s more, drugs that target amyloid-beta plaques have not been successful in treating dementia. Having said that, it’s well-known that poor-quality sleep increases dementia risk, and the research cited in this article supports that finding, and further shows that lack of sleep physically alters the brain.

My Takeaway

As with most self-reported studies, this one has its limitations. However, some interesting patterns did emerge. For instance, both the short- and long-sleep duration groups reported more depressive symptoms than the normal sleep group.

While self-reported caffeine intake didn’t appear to influence sleep, alcohol consumption did. It seems the more alcoholic drinks participants drank daily, the more likely they were to sleep longer.

If you need some guidance to improve your sleep habits, then try these tips from the Sleep Foundation for practicing good sleep hygiene: set a regular sleep schedule, follow a nightly pre-sleep routine, cut down on caffeine, especially in the afternoon and evening, and restrict in-bed activities such as watching television or eating.⁵ For more good sleep hygiene tips, go to https://www.sleepfoundation.org/sleep-hygiene

Summary

A new study from researchers at the University of California, Berkeley, and Stanford University highlights the crucial role sleep plays in protecting brain health. Their findings suggest that both sleep deprivation (six hours or less) and excessive sleep (nine or more hours) can negatively impact cognitive function. Short sleep duration is linked to higher levels of amyloid beta, a protein associated with Alzheimer’s disease, while long sleep durations correlate with weaker executive function and depressive symptoms. The research underscores the importance of maintaining a consistent seven to eight hours of sleep per night for optimal brain health, cognitive function, and memory retention.

Frequently Asked Questions

How does lack of sleep increase the risk of Alzheimer’s disease?

Sleep deprivation leads to a buildup of amyloid beta proteins in the brain, which are strongly associated with Alzheimer’s disease development.

Can too much sleep be harmful to brain health?

Yes, excessive sleep (nine or more hours) has been linked to reduced cognitive function and higher rates of depressive symptoms, though it doesn’t appear to increase amyloid beta levels.

What is the ideal amount of sleep for optimal brain health?

Research suggests that seven to eight hours of quality sleep per night is the “sweet spot” for preserving memory and cognitive function.

Does poor sleep quality impact dementia risk even if I get enough hours?

Yes, fragmented or poor-quality sleep can still increase the risk of cognitive decline and memory issues, even if you’re getting the right amount of sleep.

What are some effective ways to improve sleep for better brain health?

Practicing good sleep hygiene, such as setting a regular sleep schedule, avoiding caffeine and alcohol before bed, and creating a restful sleep environment, can help improve sleep quality and cognitive function.