Deep Sleep Helps the Brain Wash Away Alzheimer’s Toxins

It is somewhat common knowledge that the reason sleep is important has much to do with processing information from the day before.  Recent studies, though, suggest that the brain waves we generate after we reach deep sleep states appear to initiate a cleaning system in the brain that helps to protect against neurodegenerative diseases, like Alzheimer’s disease. 

Specifically, the new research identifies that electrical signals called slow waves appear the moment before a pulse of cerebrospinal fluid (CSF) passes through the brain, effectively washing away toxins that we now associate with Alzheimer’s disease.  Scientists say this discovery could serve to explain the mysteries we have yet to solve in regards to  the link between sleep and Alzheimer’s disease.

According to study co-author Laura Lewis, “We’ve known for a while that there are these electrical waves of activity in the neurons.” 

The Boston University College of Engineering assistant professor of biomedical engineering goes on to say, “But before now, we didn’t realize that there are actually waves in the CSF, too.”

Also a faculty member with the Center for Systems Neuroscience, Lewis jests at the sheer volume of people who want to volunteer for a study like this, as you basically get paid to sleep.  In all seriousness, though, she corrects, their job is actually the hardest part of the study.  Even with all the fancy new equipment, the most common problem—which also tends to be the most complicated—is that people can’t just fall asleep in these loud metal tubes.  

All that aside, the research demonstrates that when CSF is present, there are typically large, slow waves that occur about once every 20 seconds. They go on to describe that these waves appear kind of like oscillations in an extremely slow washing machine.  Combining this with the discovery of the timing of the wash, the researchers conclude that they must be related: that each electrical wave must be triggering regular wash cycles. 

It is already known that Alzheimer’s patients have fewer of these waves so the new study, then, certainly suggests that the lower frequency or intensity of these waves limit the brain’s ability to clear out the toxins that lead to Alzheimer’s disease. 

The results of this study have been published in the journal Science.