About 70 million Americans suffer from sleep problems and about 60 percent chronically don’t get adequate slumber, according to the National Center on Sleep Disorders Research.
Now there’s evidence sleeping fitfully or not enough can do far more than make you grumpy and tired the next day — a lack of restful sleep may also be triggering brain changes that eventually result in memory loss.
Scientists at the University of California, Berkeley (UC Berkeley), have found compelling evidence that not getting enough deep, restorative sleep can disrupt the brain’s ability to hold on to memory. It may even be an important factor in the development of memory-robbing Alzheimer’s disease.
“Sleep is helping wash away toxic proteins at night, preventing them from building up and from potentially destroying brain cells,” said UC Berkeley neuroscience professor Matthew Walker, PhD. “It’s providing a power cleanse for the brain.”
Walker and his research team used brain imaging and other diagnostic tools to look for links between bad sleep and poor memory in 26 older adults who were not diagnosed with dementia or other neurodegenerative, sleep, or psychiatric disorders. Specifically, the researchers wanted to see if there was a relationship between non-restful sleep, memory, and the accumulation of plaques of beta-amyloid proteins, which block communication between nerve cells, in the brains of the volunteers. Beta-amyloid deposits in the part of the brain where long-term memories reside (the prefrontal cortex) are prime suspects in causing the memory loss of Alzheimer’s disease.
The research volunteers received positron emission tomography scans to measure any beta-amyloid in their brains. Then they memorized 120 word pairs and were given a test to see how well they remembered the paired words.
After sleeping for 8 hours, during which electroencephalographic measured their brain waves, the volunteers’ brains were scanned with functional magnetic resonance imaging as they attempted to remember the previously memorized word pairs. During this test, the researchers tracked activity in the hippocampus, the part of the brain where memories are temporarily stored before they move to the prefrontal cortex.
The results revealed those who had the poorest quality sleep had the most beta-amyloid plaques in the frontal cortex. They also performed the worst on the memory test, with some forgetting more than half of the information they had memorized just the day before.
“The more you remember following a good night of sleep, the less you depend on the hippocampus and the more you use the cortex,” Walker said. “It’s the equivalent of retrieving files from the safe storage site of your computer’s hard drive, rather than the temporary storage of a USB stick.”
Is this a “which came first, the chicken or the egg” scenario? Does non-restorative sleep contribute to beta-amyloid plaques or do the plaques keep people from sleeping soundly?
“The more beta-amyloid you have in certain parts of your brain, the less deep sleep you get and, consequently, the worse your memory,” Walker said. “Additionally, the less deep sleep you have the less effective you are at clearing out this bad protein. It’s a vicious cycle. But we don’t yet know which of these two factors — the bad sleep or the bad protein — initially begins this cycle. Which one is the finger that flicks the first domino, triggering the cascade?”
The UC Berkeley team concluded not getting good sleep is an important factor in the memory decline of Alzheimer’s. However, that is potentially good news for preventing and also treating the dread disease.
“This discovery offers hope,” Walker said. “Sleep could be a novel therapeutic target for fighting back against memory impairment in older adults and even those with dementia.”
If you have trouble sleeping, check out our Sleep Care section for tips to help you get a good night’s rest.
August 20, 2015
Janet O’Dell, RN