A team of neurologists, stem cell specialists and molecular biologists affiliated with several institutions in the U.S. and led by a group at Stanford University School of Medicine has found evidence that the root cause of Alzheimer's disease may be fat buildup in brain cells. The study is published in the journal Nature.
This is an oversimplification of processes that happen during sleep. This has to do with fat metabolism in brain cells mediated through the effect of specific gene variants.