These findings provide some evidence that reduced slow wave sleep (SWS) and rapid eye movement sleep (REM) may contribute to brain atrophy, thereby increasing the risk of Alzheimer disease (AD).

Shorter slow wave sleep and rapid eye movement sleep were associated with decreased volume in Alzheimer disease-vulnerable brain regions.

There was an association between having less REM with smaller volumes of the inferior parietal region and precuneus (β = −75.54 and −31.92 mm 3 per −1 percentage point of REM, respectively).