Is Your Brain Getting Its Nightly Detox? What Science Says About Sleep and Alzheimer’s

More than 6.7 million Americans aged 65 and older are currently living with Alzheimer’s disease, and that number is expected to double by 2060. While memory loss is the most visible symptom, changes in the brain can begin years before.

And one of the earliest factors linked to these changes? How well you sleep.

A 2023 study from Yale, published in the Journal of Clinical Sleep Medicine, followed over 270 adults and found that people who spent less time in deep and REM sleep had smaller brain volumes in areas known to shrink early in Alzheimer’s. This included regions such as the inferior parietal lobe, which plays a crucial role in memory and learning. What’s striking is that these brain changes were measured more than a decade after the sleep data were collected.

Even after adjusting for factors like blood pressure, alcohol use, and general health, the connection remained. The takeaway is clear: certain stages of sleep may play a bigger role in long-term brain health than most people realize.

Why Do Deep Sleep and REM Matter So Much?

Deep sleep, also called slow-wave sleep (SWS), is when your brain gets the chance to repair and reset. During this stage, brain activity slows down and the body reaches its most restful state [2]. What makes this phase so important is that it activates the brain’s natural cleaning system, known as the glymphatic system. This system moves fluid through brain tissue to sweep away waste, including proteins like amyloid-beta and tau.

These proteins form naturally during the day, but if they’re not cleared out during sleep, they can start to build up. Over time, that buildup has been linked to the development of Alzheimer’s disease [3].

REM sleep, the stage where dreaming happens, is also essential. It helps consolidate memory and process emotions. In the Yale study, both deep sleep and REM were tied to brain structure, suggesting that sleep architecture—the balance of different stages—may be more important than sleep quantity alone.

How Can Missing These Sleep Stages Affect Your Brain Over Time?

Missing a night of sleep here and there isn’t the issue. It’s the pattern of poor sleep that slowly adds up.

Research shows that disrupted deep and REM sleep can make it harder for the brain to clear out harmful waste. Here’s what other studies have found:

• One PET scan study revealed that just one night of total sleep loss led to an increase in beta-amyloid, especially in memory-related areas like the hippocampus [4].
  
  

• Another study found a spike in tau protein levels in the bloodstream after a single night of poor sleep [5].
  
  

• People who routinely sleep fewer than six hours a night face a 30% higher risk of developing dementia later in life [5].
  
  

• Long-term sleep problems appear to reduce the brain’s ability to protect itself from damage [5].

As Gawon Cho, a postdoctoral associate at Yale School of Medicine, explained to the American Academy of Sleep Medicine:

 “Reduced neuroactivity during sleep may contribute to brain atrophy, thereby potentially increasing the risk of Alzheimer’s disease.”

The research is growing, and the message is consistent. How you sleep now may affect how your brain ages in the years ahead.

Also Read: Not Getting Enough Deep Sleep? Study Links 27% Higher Risk of Dementia to Poor Sleep

Are Sleep Changes an Early Sign of Alzheimer’s?

In many cases, yes.

Before memory loss begins, people often experience subtle sleep changes. These may include:

• Waking up frequently during the night
  
  

• Feeling tired even after a full night of sleep
  
  

• Sleeping at irregular times or taking frequent naps
  
  

• Less dream recall or lighter, more fragmented sleep

Studies suggest that these shifts in sleep may show up long before other symptoms. Alzheimer’s can also interfere with the brain’s internal clock, disrupting the signals that control sleep timing and rhythm [5].

This creates a two-way cycle. Poor sleep may increase Alzheimer’s risk, and early Alzheimer’s changes may, in turn, make it harder to sleep well. Over time, this feedback loop can make symptoms worse if left unchecked.

Why Does Deep Sleep Decline With Age?

It’s common for sleep to feel lighter or more disrupted with age. One reason is that deep sleep naturally declines over time.

Most adults in their 20s spend about 15 to 20 percent of the night in deep sleep. By the time someone reaches their 60s or 70s, that number can drop to below 5 percent [6].

Several factors contribute:

• Changes in the brain’s sleep centers
  
  

• More frequent nighttime awakenings
  
  

• Medical conditions or medications that interrupt sleep
  
  

• Shifted sleep-wake rhythms that cause earlier wake times

As deep sleep decreases, the brain’s cleanup system also becomes less active. That means proteins like amyloid and tau may not get flushed out as efficiently, increasing the potential for long-term buildup.

This doesn’t mean poor sleep is inevitable as you age, but it does highlight the importance of supporting quality sleep earlier in life and maintaining it as much as possible.

Also Read: How to Sleep Better as You Get Older

What Can You Do to Support Better Sleep for Brain Health?

There’s no single solution for better sleep, but small changes can add up. These daily habits can help improve your chances of getting the deep and REM sleep your brain needs:

• Go to bed and wake up at the same time each day
  
  

• Get sunlight in the morning to help regulate your body clock
  
  

• Avoid caffeine and alcohol in the evening
  
  

• Create a calming nighttime routine
  
  

• Keep your bedroom cool, dark, and quiet
  
  

• Try using a pink noise machine to help you stay asleep and support deeper, more restorative sleep cycles

If you’ve already tried these and still struggle to get restful sleep, a gentle supplement may help. Sip2Sleep® is a melatonin-free natural sleep aid made with Montmorency Tart Cherry and Rafuma Leaf, two natural ingredients known for their calming effects. It’s taken under your tongue for fast-acting results and fits easily into an evening routine, unlike sleeping pills or melatonin supplements that may leave you groggy or disrupt your natural sleep cycle.

References:

1. (2023), 2023 Alzheimer's disease facts and figures. Alzheimer's Dement., 19: 1598-1695. https://doi.org/10.1002/alz.13016

2. Ma, J., Chen, M., Liu, GH. et al. Effects of sleep on the glymphatic functioning and multimodal human brain network affecting memory in older adults. Mol Psychiatry 30, 1717–1729 (2025). https://doi.org/10.1038/s41380-024-02778-0

3. Nicolazzo J, Cavuoto M, Rowsthorn E, Cribb L, Bransby L, Gibson M, Wall P, Velakoulis D, Eratne D, Buckley R, Yassi N, Yiallourou S, Brodtmann A, Hamilton GS, Naughton MT, Lim YY, Pase MP. Insomnia Symptoms and Biomarkers of Alzheimer's Disease in the Community. J Alzheimers Dis. 2023;91(4):1423-1434. doi: 10.3233/JAD-220924. PMID: 36641673; PMCID: PMC11446570.

4. Shokri-Kojori E, Wang GJ, Wiers CE, Demiral SB, Guo M, Kim SW, Lindgren E, Ramirez V, Zehra A, Freeman C, Miller G, Manza P, Srivastava T, De Santi S, Tomasi D, Benveniste H, Volkow ND. β-Amyloid accumulation in the human brain after one night of sleep deprivation. Proc Natl Acad Sci U S A. 2018 Apr 24;115(17):4483-4488. doi: 10.1073/pnas.1721694115. Epub 2018 Apr 9. PMID: 29632177; PMCID: PMC5924922.

5. Benedict C, Blennow K, Zetterberg H, Cedernaes J. Effects of acute sleep loss on diurnal plasma dynamics of CNS health biomarkers in young men. Neurology. 2020 Mar 17;94(11):e1181-e1189. doi: 10.1212/WNL.0000000000008866. Epub 2020 Jan 8. PMID: 31915189; PMCID: PMC7220231.

6. Van Cauter E, Leproult R, Plat L. Age-Related Changes in Slow Wave Sleep and REM Sleep and Relationship With Growth Hormone and Cortisol Levels in Healthy Men. JAMA. 2000;284(7):861–868. doi:10.1001/jama.284.7.861