New studies illuminate mysterious connection between sleep and Alzheimer's disease

A growing body of research suggests that healthy sleep habits might be effective in preventing the onset of Alzheimer's disease.


The exact functions of sleep remain a mystery to scientists. Although studies suggest that a healthy sleep schedule helps people regulate their emotions, perform better on cognitive tasks, and even live longer, it’s still unclear exactly what the body is doing during sleep to bring about these positive effects.

However, one recent hypothesis suggests the brain uses its downtime to run a ‘cleaning cycle’ during which it removes metabolic debris, like amyloid beta (A-beta), the main component of the sticky plaques found in the brains of people with Alzheimer’s disease. According to the hypothesis, poor sleep hinders the brain’s ability to remove A-beta and over time the plaques build up. This puts people at greater risk of developing Alzheimer’s disease.

In 2013, scientists made an important discovery about the brain’s cleaning functions during sleep. The brain is the only organ that’s not connected to the lymphatic system, which removes waste and toxins from the body via the liver. Maiken Nedergaard, a neuroscientist at the University of Rochester in New York, thought that maybe the brain has a similar system, one scientists had yet to discover.

“I found it weird because the brain is our most precious organ—why should it be the only organ that recycles its own proteins?” Nedergaard told Science News.

To find out, Nedergaard and her team conducted a study on mice in which they tracked the flow of cerebrospinal fluid through their brains. They found that during sleep the spaces between mice’s brain cells widened by more than half, allowing fluid to wash through and carry away metabolic debris like A-beta.

“It’s like the dishwasher turned on,” Nedergaard said, adding that she dubbed this the ‘glymphatic system’ because it seems to be controlled by the brain’s glial cells.

Sleep quality seems to play a major role in how efficiently the brain removes A-beta.


In a study published in April 2018, participants showed a 5% increase in A-beta accumulation after they had been deprived of sleep for 31 hours. The build-up occurred in the thalamus and hippocampus, regions of the brain that Alzheimer’s disease often hits first.

“I was surprised that it was actually so large,” study coauthor Ehsan Shokri-Kojori, now at the National Institute on Alcohol Abuse and Alcoholism, told Science News. “Five percent from one night of sleep deprivation is far from trivial.”

Another study published in June hints at a similar link between sleep quality and A-beta accumulation. In the study, researchers asked 283 elderly participants to answer questions about their health and sleep habits, and also to undergo multiple PiB-PET scans to measure A-beta levels in the brain.

The results suggested that people who got less sleep had higher levels of A-beta in their brains both at the start and end of the study.

The potential link between sleep habits and Alzheimer’s disease might seem disconcerting, but it would also illuminate a path toward treating and possibly preventing the disease that affects some 5.7 million Americans.

“If we find out that sleep problems contribute to brain amyloid—what that really says is there may be a window to intervene,” Neuroscientist Barbara Bendlin told Science News.


3D printing might save your life one day. It's transforming medicine and health care.

What can 3D printing do for medicine? The "sky is the limit," says Northwell Health researcher Dr. Todd Goldstein.

Northwell Health
Sponsored by Northwell Health
  • Medical professionals are currently using 3D printers to create prosthetics and patient-specific organ models that doctors can use to prepare for surgery.
  • Eventually, scientists hope to print patient-specific organs that can be transplanted safely into the human body.
  • Northwell Health, New York State's largest health care provider, is pioneering 3D printing in medicine in three key ways.
Keep reading Show less

Adam Gopnik on the rhinoceros of liberalism vs. the unicorns of everything else

Torn between absolutism on the left and the right, classical liberalism—with its core values of compassion and incremental progress whereby the once-radical becomes the mainstream—is in need of a good defense. And Adam Gopnik is its lawyer.

Think Again Podcasts
  • Liberalism as "radical pragmatism"
  • Intersectionality and civic discourse
  • How "a thousand small sanities" tackled drunk driving, normalized gay marriage, and could control gun violence
Keep reading Show less

Why the south of Westeros is the north of Ireland

As Game of Thrones ends, a revealing resolution to its perplexing geography.

Image: YouTube / Doosh
Strange Maps
  • The fantasy world of Game of Thrones was inspired by real places and events.
  • But the map of Westeros is a good example of the perplexing relation between fantasy and reality.
  • Like Britain, it has a Wall in the North, but the map only really clicks into place if you add Ireland.
Keep reading Show less

Fascism and conspiracy theories: The symptoms of broken communication

The lost practice of face-to-face communication has made the world a more extreme place.

Videos
  • The world was saner when we spoke face-to-face, argues John Cameron Mitchell. Not looking someone in the eye when you talk to them raises the potential for miscommunication and conflict.
  • Social media has been an incredible force for activism and human rights, but it's also negatively affected our relationship with the media. We are now bombarded 24/7 with news that either drives us to anger or apathy.
  • Sitting behind a screen makes polarization worse, and polarization is fertile ground for conspiracy theories and fascism, which Cameron describes as irrationally blaming someone else for your problems.
Keep reading Show less