Wake-up call: How a lack of sleep can cause Alzheimer’s

tl;dr, from this source and related others: The vertebrate CNS has its own waste clearance system, called the "glymphatic system", which serves a similar function as the lymphatic system does for the rest of the organism. During slow-wave sleep, neurons contract to increase the volume of extracellular space, which aids the glymphatic system in clearing toxins such as the β-amyloids which recent research strongly implicates as a risk factor for Alzheimer's. It is therefore reasonable to suspect that restriction of slow-wave sleep, such that this clearance cannot occur or can't run to completion, itself poses a risk of Alzheimer's, and perhaps other disorders, later in life.