Disrupted sleep was linked to a higher risk of developing Alzheimer's in a new study by US scientists.

Researchers from Washington University School of Medicine in St. Louis found that the brains of people with poor sleep patterns have a greater build-up of amyloid plaque -- clumps of protein that are a key marker of Alzheimer's.

The team monitored the sleep patterns of 100 healthy volunteers aged between 45 and 80, half who had a family history of Alzheimer's, for 14 nights.

They found that those who woke more than five times an hour, and participants who spent less than 85 percent of their time in bed actually sleeping, were more likely to have amyloid plaque build-up in their brains than those who did not wake up as much.

Dr. Yo-El Ju, lead author of the study, said, "Disrupted sleep appears to be associated with the build-up of amyloid plaques, a hallmark marker of Alzheimer's disease, in the brains of people without memory problems."

He added, "Further research is needed to determine why this is happening and whether sleep changes may predict cognitive decline. The association between disrupted sleep and amyloid plaques is intriguing, but the information from this study can't determine a cause-effect relationship or the direction of this relationship."

The study authors, who will present the research at the American Academy of Neurology meeting in New Orleans in April, said their findings provided the groundwork for investigating whether manipulating a person's sleep could slow down, or prevent, Alzheimer's.