New research has shown that a bad night’s sleep leads to more than just grumpiness the next day; it can also increase the risk of Alzheimer's disease.
Scientists from Washington University School of Medicine, Missouri, Radboud University Medical Centre in the Netherlands and Stanford University, California, discovered just one night of unrest in healthy, middle-aged adults causes an increase in amyloid beta, a brain protein linked to Alzheimer's.
A group of 17 participants was analysed for the study, all aged 35 to 65 with no history of chronic sleep problems or mental impairments. The volunteers spent a night in a sound-proofed room, wearing headphones, and their brainwaves were monitored.
Some of the test group were allowed to enjoy a night of peaceful sleep while others were randomly assigned to be awoken by having bleeps played into their headphones. The process was repeated around a month later, though the groups were reversed and the previously undisturbed sleepers had their rest interpreted the second time around.
It was found that after one night of interrupted sleep amyloid beta levels were up 10 per cent. However there were no changes to levels of tau, another protein linked to Alzheimer's. Tau levels did increase in the participants who slept poorly in the week leading up to the study though.
“We showed that poor sleep is associated with higher levels of two Alzheimer's-associated proteins,” summarised lead author Professor David Holtzman, of Washington University School of Medicine.
“We think that perhaps chronic poor sleep during middle age may increase the risk of Alzheimer's later in life.”
Co-author Dr Yo-El Ju added that the team “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,” Ju explained. “But we could see, when the participants had several bad nights in a row at home, that their tau levels had risen.”
The study has been published in journal Brain.
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