Too much deep sleep can delay the onset of dementia by ‘washing’ the brain

Getting a good night’s sleep can delay the onset of dementia later in life, scientists have found.

The way people sleep can be used as a “crystal ball” to predict whether they will suffer from Alzheimer’s disease in the future, according to the researchers.

Deep sleep was found to best delay the onset of dementia because it delays the build-up of a toxic plaque in the brain called beta-amyloid.

Study co-author Professor Matthew Walker said: “We found that the dream you are having right now is almost like a crystal ball telling you when and how quickly Alzheimer’s disease will develop in your brain. The silver lining here is that there is something we can do about it.

“The brain is washed during deep sleep, so there may be the possibility of turning back the clock by sleeping earlier in life.”

When we sleep, we move between REM (rapid eye movement) sleep and non-REM sleep. During REM sleep, your eyes move rapidly in different directions and you are more likely to dream.

The UC Berkeley in California study looked at the sleep quality of 32 healthy adults ages 60, 70 and 80.

Each participant spent eight hours sleeping while the tests recorded brain waves, heart rate, blood oxygen levels and the growth of beta-amyloid plaque.

Participants who experienced “fragmented” or non-REM slow-wave sleep to begin with had more beta-amyloid plaques over the course of the study.

Co-author Joseph Winer from Stanford University said: “Instead of waiting for someone to develop dementia, we can assess how sleep quality predicts changes in beta-amyloid plaques at multiple time points.

“By doing so, we can measure how quickly this toxic protein accumulates in the brain over time.”