Glymphatic System and Alzheimer’s: Amyloid and Tau

Doctoral student Marta Arbizu Gómez presents recent evidence on how sleep helps prevent Alzheimer’s disease.

A study published in Nature Communications (2026) demonstrates that NREM sleep activates the glymphatic system to facilitate the clearance of beta-amyloid and tau protein. During physiological rest, the increase in these markers in the blood confirms effective central clearance, whereas sleep deprivation compromises their elimination. These findings are decisive for interpreting plasma biomarkers in neuropsychological assessment. They also support integrating rest as a modifiable factor alongside cognitive rehabilitation on platforms such as NeuronUP.

Can sleep protect our brains?

Alzheimer’s disease (AD) is a complex condition involving multiple factors, from genetics to lifestyle. Among the latter, sleep has gained increasing prominence.

Poor sleep has been associated in numerous studies with an increased risk of cognitive decline and Alzheimer’s disease. However, until recently it was unclear what exactly happens in the brain during sleep to explain this relationship.

A recent study published in Nature Communications in 2026 provides a key piece of the puzzle: while we sleep, the brain activates a “cleanup” system that removes proteins associated with Alzheimer’s disease.

How was the research on the glymphatic system and Alzheimer’s disease conducted?

To investigate this phenomenon, the researchers designed a study using a very direct approach.

Healthy individuals took part and experienced two types of night:

One night sleeping normally;
and one night without sleep (sleep deprivation)

Before and after each night, key proteins associated with Alzheimer’s disease were measured in the blood, including:

Beta-amyloid (Aβ),
and tau.

In addition, brain activity was recorded during the night, along with other physiological indicators, to better understand what was happening in the brain.

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What do the key findings of this research reveal?

The results help clarify the role of sleep in brain health.

More proteins in the blood… But for a good reason

After a night of normal sleep, blood levels of Aβ and tau were higher than after a night without sleep.

Although this may seem negative, it actually indicates the opposite. During sleep, the brain expels these proteins into the bloodstream, facilitating their elimination.

Poor sleep reduces the brain’s “cleanup”

When participants did not sleep:

The passage of these proteins into the blood decreased;
and their elimination was reduced.

This suggests that the brain is cleaned less effectively when we do not sleep, which could promote the accumulation of these proteins over time.

Deep sleep plays a key role

Not all sleep has the same effect. The study shows that deep sleep (NREM) is especially important because this is when:

The brain is more disconnected;
and cleanup mechanisms are most active.

Therefore, the better the quality of sleep, the greater the elimination of proteins.

Production and elimination: a constant balance

In the brain, two processes occur at the same time:

Proteins such as Aβ and tau are produced;
and they are eliminated through the cleanup system.

During sleep, elimination predominates, whereas during wakefulness (and especially with sleep deprivation), production predominates. The problem arises when this balance is disrupted.

Overall, these findings point to a key role for sleep in eliminating proteins associated with Alzheimer’s disease. To facilitate interpretation of these results, the summary table below presents the study’s main findings:

Aspect	Result
Study type	Human crossover trial
Participants	Healthy adults
Conditions	Sleep vs. sleep deprivation
Main outcome	Greater elimination of beta-amyloid and tau during sleep
Role of deep sleep	Key to brain cleanup
Effect of not sleeping	Reduced elimination and possible accumulation

Table 1. Summary of the main study results on the role of sleep in eliminating proteins associated with Alzheimer’s disease.

Why might this effect occur?

The study points to a specific system responsible for this cleanup: the glymphatic system. This system functions as a drainage network that allows fluids in the brain to circulate and remove waste.

During sleep:

The brain reduces its activity;
fluid flow increases;
and protein elimination is facilitated.

When we do not sleep, this system functions less effectively, reducing its cleaning capacity.

What implications does this study on the glymphatic system and Alzheimer’s disease have for clinical practice?

Although this was a short-term study in healthy individuals, the results have important implications:

Prevention of cognitive decline

Good sleep could be a key factor in reducing the risk of protein accumulation associated with Alzheimer’s disease.

Importance of sleep quality

It is not only important to sleep for many hours, but also to sleep well, especially to reach deep sleep stages.

Interpretation of biomarkers

Blood protein levels may vary depending on sleep, which is relevant in the clinical context.

How does this advance relate to NeuronUP?

At NeuronUP, a cognitive assessment and rehabilitation platform, we take an integrated approach to cognitive decline, in which not only the intervention matters, but also the factors that influence brain health.

This study provides key information to:

Identify sleep as a modifiable factor in cognitive risk;
complement cognitive rehabilitation with healthy habits;
and design more personalized interventions.

Combining cognitive training with healthy lifestyle habits, such as sleep, is essential for maintaining brain function.

Study limitations

It is important to interpret these results with caution:

The number of participants was relatively small;
this was a short-term study;
and it included only healthy individuals.

Therefore, more studies will be needed to confirm these findings in clinical populations and over the long term.

Conclusion

Sleep is important not only for rest, but also for keeping the brain healthy. This study demonstrates that during sleep, a cleanup system is activated that removes proteins associated with Alzheimer’s disease, whereas sleep deprivation reduces this process.

These results reinforce an increasingly clear idea: sleep quality is a key factor in brain health and could play an important role in preventing Alzheimer’s disease.

References

Dagum P, Elbert DL, Giovangrandi L, Singh T, Venkatesh VV, Corbellini A, Kaplan RM, Rane Levendovszky S, Ludington E, Yarasheski K, Lowenkron J, VandeWeerd C, Lim MM, Iliff JJ. The glymphatic system clears amyloid beta and tau from brain to plasma in humans. Nature Communications. 2026. doi:10.1038/s41467-026-68374-8.

Frequently asked questions about sleep and biological brain aging

1. How does sleep help prevent Alzheimer’s disease?

During rest, the brain activates the glymphatic system, a drainage network that removes proteins associated with Alzheimer’s disease, such as beta-amyloid and tau, by expelling them into the bloodstream for subsequent elimination.

2. Why do Alzheimer’s-related proteins increase in the blood after a good night’s sleep?

Adequate rest increases the rate of brain clearance, releasing these proteins into the plasma for elimination. An elevated plasma level reflects effective central clearance, whereas reduced levels after sleep deprivation indicate retention in the brain parenchyma.

3. What happens to the brain during sleep deprivation?

Lack of rest reduces the glymphatic system’s clearance capacity. As a result, toxic proteins do not enter the bloodstream and tend to accumulate in brain tissue over time.

4. Why is the deep sleep (NREM) phase so important?

During the NREM phase, neuronal activity decreases and the brain’s interstitial space expands, reaching the highest rate of fluid circulation and metabolic clearance.

5. How does sleep hygiene influence cognitive stimulation programs?

Cognitive training requires an optimal neurofunctional reserve and a brain parenchymal environment free of neurotoxins. Integrating sleep management as a modifiable factor into cognitive rehabilitation guidelines enhances neuroplasticity and slows the progression of preclinical cognitive decline.