Health

What Happens to Your Brain When You Don't Sleep Enough

Researchers have long theorized about the possible relationship between sleep and Alzheimer's disease — a progressive mental disease that affects memory and other brain functions — but until recently, the relationship has been shrouded in uncertainty. While many Alzheimer's patients have reported poor sleep habits, that was initially considered an effect of the disease on the part of the brain that regulates sleep. 

Now studies are showing increasing evidence that a lack of deep sleep may put people at greater risk of developing Alzheimer's disease. When you don't get enough rest, toxins associated with the disease build up and cause damage to the brain, researchers at Oregon Health & Science University found. 

"Changes in sleep habits may actually be setting the stage [for Alzheimer's disease]," Dr. Jeffrey Iliff, a brain scientist at Oregon Health & Science University, told NPR. To verify that theory, Iliff and his colleagues plan to launch a study within the next year that "should clarify the link between sleep problems and Alzheimer's disease in humans." 

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The benefits of a good night's rest are many, but one of the most important functions of sleep is the flushing out of toxins such as amyloid plaques in the brain. This study was a follow-up from a 2009 study conducted by researchers at Washington University in St. Louis, which showed that, in lab mice that were sleep deprived, the accumulation of these sticky plaques — which are common among Alzheimer's patients — occurred faster than in the restful test subjects.

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Then, in 2013, Iliff and and his peers used that finding to conduct tests that determined that such toxins were cleansed from the brain through the organ's glymphatic system.

During deep sleep, "the fluid that's normally on the outside of the brain, cerebrospinal fluid — it's a clean, clear fluid — it actually begins to recirculate back into and through the brain along the outsides of blood vessels," Iliff told NPR. "That suggests at least one possible way that disruption in sleep may predispose toward Alzheimer's disease." 

In order to assess how this process relates to the development of this degenerative mental disease in human test subjects, however, Iliff and his colleagues plan to use of the world's most powerful magnetic resonance imaging machines to peer into their brains during sleep and determine when and how the glymphatic system is functioning.

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For young, healthy people, there should be clear signs — namely, changes in signals that come from salt molecules in the brain — that the system is working properly. But for older people, especially those at risk of developing Alzheimer's, there should be differences in the strength of those signals.

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"If Rooney and Iliff are right, the experiment will greatly strengthen the argument that a lack of sleep can lead to Alzheimer's disease," NPR reported. "It might also provide a way to identify people whose health is at risk because they aren't getting enough deep sleep, and it could pave the way to new treatments."