Scientists have shown that a single night of interrupted sleep can cause an increase in brain proteins associated with Alzheimer’s disease.
The findings could answer the question of how broken sleep is possibly linked to Alzheimer’s and could help protect those who suffer from chronic sleep deprivation.
“We showed that poor sleep is associated with higher levels of two Alzheimer’s-associated proteins,” said one of the researchers, David M Holtzman, from Washington University. “We think that perhaps chronic, poor sleep during middle age may increase the risk of Alzheimer’s later in life.”
Scientists are working on finding out the exact causes of Alzheimer’s, but two proteins found in the brain have been identified as key indicators of the disease. Previous research has shown a connection between disturbed sleep and cognitive impairment, including Alzheimer’s disease, but the mechanisms are still unclear.
The scientists took 17 healthy adults, between the ages of 35 and 65, who had no history of sleep problems. They fitted them with an activity monitor to keep a record of how much they’d slept in the previous two weeks. Although the activity monitor provided valuable information, the most interesting data came from the sleep laboratory.
The sleep lab is a dark room that contains a good bed, is soundproof and climate controlled. The participants were fitted with electrodes on their scalp, to monitor brain activity, and headphones to allow the scientists to subtly control their sleep patterns.
During the study, half of the participants were assigned to have their sleep interrupted while bunking at the sleep lab.
“At this point, we can’t say whether improving sleep will reduce your risk of developing Alzheimer’s. All we can really say is that bad sleep increases levels of some proteins that are associated with Alzheimer’s disease. But a good night’s sleep is something you want to be striving for anyway.”
Washington University researcher, Yo-El Ju
Every time they entered a sleeping stage with slow-wave patterns (characteristic of a deep restful and dreamless sleep) a series of beeps were sent through the headphones until the brainwaves increased in activity.
The next morning, the participants who had had their sleep interrupted said they were tired and felt un-refreshed. Interestingly, they didn’t often remember being awakened by the noise in the headphones.
At this point, the sleep chamber became a little more gruesome than relaxing.
To measure the levels of proteins in the cerebral fluid after the night of sleep, needles were pushed into the participant’s spinal cords and samples of spinal fluid was taken.
The researchers found that there was a ten percent increase in amyloid beta in those who had been disrupted during slow-wave sleep for one night.
It wasn’t until the team looked at the activity monitors of the previous two weeks that a connection between the presence of the protein “tau” and longer periods of sleep deprivation was made.
But there’s some good news hidden in the results for restless sleepers.
The scientists aren’t convinced that one night of sleep poses a significant risk in developing Alzheimer’s. It’s likely that the negative effects are reversed once you return to sleeping normally.
Once you are able to get a good amount of slow-wave sleep it removes the build-up of by-products from the cerebral fluid.
The problem lies with those experiencing more serious, chronic sleeping problems.
Health-e reporting with sources: Journal Brain; Science Alert