Association Between Slow-Wave Sleep Loss and Incident Dementia https://jamanetwork.com/journals/jamaneurology/fullarticle/2810957 Low levels of slow-wave sleep were linked to a higher risk of cardiovascular disease and having the APOE ε4 gene, which is linked to Alzheimer's https://www.sciencealert.com/one-stage-of-sleep-seems-critical-for-reducing-risk-of-dementia