The relationship between good sleep and Alzheimer’s disease

By Liz Lockhart

Your memory could be affected in later life by the amount of quality sleep you get now, according to research from the Washington University School of Medicine in St. Louis.

‘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. Further research is needed to determine why this is happening and whether sleep changes may predict cognitive decline,’ said the study author Yo-El Ju MD.

In the study 100 people aged between 45 and 80 who were free of dementia were tested by researchers. Half of the participants had a family history of Alzheimer’s disease. Over a two week period a device was placed on the participants to measure sleep. They also kept diaries and completed questionnaires which were analysed by the researchers.

It was found that 25% of the participants had evidence of amyloid plaques. These can appear years before the signs of Alzheimer’s disease begin. Although the average time spent in bed during the study was about eight hours, the average amount of time spent sleeping was 6.5 hours due to short periods of wakefulness during the night.

The researchers found that the people who woke up more than five times an hour were more likely to have amyloid plaque build-up, compared to those who did not wake so much. It was also found that those people who slept ‘less efficiently’ were more likely to have the markers of Alzheimer’s disease than those who slept efficiently. Those who spent more than 85% of their time in bed actually sleeping were less likely to have the markers.

‘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. We need longer-term studies, following individuals’ sleep over years, to determine whether disrupted sleep leads to amyloid plaques, or whether brain changes in early Alzheimer’s disease lead to changes in sleep. Our study lays the groundwork for investigating whether manipulating sleep is a possible strategy in the prevention or slowing of Alzheimer disease,’ Ju concluded.