In addition to early abnormalities of DMN function, cognitively unimpaired APOE ε4 carriers have shown REM sleep duration.45 Lower REM sleep percentage and longer latency to REM from sleep onset have been associated with an increased risk of dementia, including AD,46 consistent with associations between prolonged REM latency and Aβ.47 This might suggest that APOE ε4 carriers and individuals with AD-neuropathology have reduced recall for dreams because of less REM sleep and therefore fewer dreams. Here, APOE is linked to Alzheimer disease.