A new study says those restless nights could harm more than just your mood the next morning. Researchers at Washington University in St. Louis, Missouri, found that poor sleep was linked to an increase in proteins associated with Alzheimer’s Disease: amyloid beta and tau.

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For the very small study, 17 adults between 35 and 65 years old wore an activity monitor for two weeks to measure their sleep patterns. After five nights, participants spent one evening in a dark, sound-proof sleep room. Half of the subjects were able to snooze through the night while the other half were interrupted by beeps administered any time they fell into a deeper, slow-wave pattern sleep. According to Harvard University, this is the hardest stage to wake up from and is also the point where our brains are most relaxed.

The sounds were administered through headphones worn by all participants. Unsurprisingly, those who were interrupted felt tired and unrefreshed the next morning, even though they slept for the same length of time as the group who went undisturbed. What’s more, even though they felt the physical effects of poor sleep quality, they couldn’t remember the beeping.

Scientists then took a spinal tap sample from each person to measure amyloid beta and tau proteins. A month later, the test was repeated. This time, people who slept through the night had to endure the beeps while those who were previously disturbed snoozed without interruption. After comparing the protein levels of people who entered slow-wave sleep and those who didn’t, researchers found a 10 percent increase in amyloid beta levels after one night of bad sleep. The tau levels had no significant change. But scientists found that people who slept poorly at home for a week (as determined by the sleep monitors), had higher levels of tau protein.

“We were not surprised to find that tau levels didn’t budge after just one night of disrupted sleep while amyloid levels did, because amyloid levels normally change more quickly than tau levels,” study co-author Yo-El Ju, assistant professor of neurology at Washington University, said in a statement. “But we could see, when the participants had several bad nights in a row at home, that their tau levels had risen.”

Prior research has shown that both tau and amyloid proteins are found in the brains of Alzheimer’s patients.

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But this doesn’t mean that a poor night’s sleep here and there will result in Alzheimer’s. Chronic sleep problems, like sleep apnea, however, can result in cognitive decline.

“Many, many Americans are chronically sleep-deprived, and it negatively affects their health in many ways,” said Ju. “At this point, we can’t say whether improving sleep will reduce your risk of developing Alzheimer’s.”

However, the researcher stresses the importance of a good night’s rest. “All we can really say is that bad sleep increases levels of some proteins that are associated with Alzheimer’s disease,” said Ju. “But a good night’s sleep is something you want to be striving for anyway.”

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