Science 4 min read

How Deep Sleep Protects the Brain From Alzheimer's



A recent study suggests that deep sleep can help clear Alzheimer’s toxins.

According to reports, nearly 5.8 million Americans of all ages are living with Alzheimer’s dementia in 2019. What’s more, analysis of the lifetime risk suggests that 20 percent of women and 10 percent of men at age 45 will develop the diseases.

While the exact cause of the diseases remains largely unknown, several cases are thought possible. An example of such a situation is the abnormal buildup of beta-amyloid or plaques in the brain.

Amyloid plaques are the clumps of proteins that accumulate outside the nerve cells.

As you can imagine, these single-molecule beta are toxic to the cells. They destroy the connection of the synapses, hence preventing neurons from communicating effectively.

The degradation in synapses ultimately leads to memory impairment. Also, it harms the patient’s ability to think, plan, and regulate emotion.

An article in the American Academy of Neurology linked a high amount of beta-amyloid in the brain with a steep memory decline in mentally healthy older people. In other words, plague buildup plays an essential role in determining whether people develop a memory disease like Alzheimer’s.

What Causes Plaque Buildup?

At the moment, researchers are still not entirely sure.

Studies have hypothesized that the gum diseases causing bacteria, P. gingivalis, could be responsible for amyloid production. However, further research is required to establish a causal link.

Luckily for us, the body’s natural defense mechanism fights the toxin. According to Randall Bateman, a professor of neurology at Washington University, the brain sweeps the amyloid buildup when we sleep.

In a statement to the press, Bateman said:

“Beta-amyloid concentrations continue to increase while a person is awake. And then after people go to sleep, that concentration of beta-amyloid decreases.”

However, the mechanism involved remained a mystery, until now. In a recent study published in the journal Science, researchers uncovered a “wash cycle” in the brain that removes the plague during sleep.

How the Brain Cleans Itself During Deep Sleep

Using cutting-edge MRI techniques and other techs, a team of scientists observed what was going on in the brain of 11 sleeping respondents. They mainly focused on cerebrospinal fluid (CSF) – a liquid that flows through the brain and spinal cord.

That was when the researchers noted something odd.

Study author and assistant professor in the department of biomedical engineering at Boston University, Laura Lewis said:

“We discovered that during sleep, there are these really large, slow waves occurring maybe once every 20 seconds of CSF washing into the brain.”

The researcher compared the waves with the oscillation of a very slow washing machine.

Although previous studies suggested that the CSF increases during deep sleep to clean toxins in the brain, Lewis’s team saw it in real-time. This led to another unexpected discovery.

According to Lewis, the wave of fluid occurred seconds after an electrical wave in the neuron. This suggests that the electrical wave was triggering each wash cycle.

Furthermore, Lewis and her team identified the brain wave as slow waves. It’s the brain activity that researchers associate with a sleep state known as deep sleep or non-rapid eye movement.

In other words, deep sleep could protect the brain from Alzheimer’s.

A professor of public health and neuroscience at the University of California, William Jagust, concluded:

“There are a bunch of things that are probably contributing to people’s likelihood [of] getting Alzheimer’s. And I think sleep is going to turn out to be one of them.”

How Much Sleep is Needed to Prevent Alzheimer’s?

As you may have guessed, it has less to do with how long you sleep and more to do with the quality of your sleep.

There are three phases of non-REM sleep, which usually last between 5 to 15 minutes. We go through all these phases before reaching REM sleep.

In the first stage, your eyes are closed, but it’s still easy to wake you up. You can spend between 5 to 10 minutes at this stage.

After that, enters the light sleep stage, where your heart rate slows and body temperature drops. It prepares your body for the final stage of non-REM sleep.

In the deep sleep stage, it’s difficult to rouse you.

That’s when your body repairs and regrows tissues and strengthens the immune system. As it turns out, the wash cycle also occurs during this stage of sleep.

There’s just one problem.

Studies suggest that as you grow older, you’re less likely to get deep sleep. That means aging could give the CSF less time to clear amyloid buildup in the brain.

While this could explain why the neurodegenerative disease is prevalent among age 65 and older, it’s still too early to tell. Further research is necessary to understand the link between Alzheimer’s and sleep.

Read More: Study Finds Alzheimer’s Symptoms Made Worse by Canola Oil Consumption

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Sumbo Bello

Sumbo Bello is a creative writer who enjoys creating data-driven content for news sites. In his spare time, he plays basketball and listens to Coldplay.

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