According to Robert Preidt in his 12 August 2019 HealthDay News report titled “Too Much Napping May Signal Alzheimer’s, . . . dozing off during the day . . . might be an early warning sign that you have Alzheimer’s disease.” (See https://www.webmd.com/alzheimers/news/20190812/too-much-napping-may-signal-alzheimers#2)
Yikes! As if those of us with MS related fatigue don’t already have enough to be concerned about.
The words, “might be,” are significant.

While Preidt’s assertion may be supported by scientific research, it can be difficult to assign a singular cause to a physical condition. According to the National Multiple Sclerosis Society, “Fatigue is one of the most common symptoms of MS, occurring in about 80 percent of people [with MS].” See NMSS video “Fatigue and MS, Part One” at https://www.youtube.com/embed/zlYpAF-Ch8U
Perhaps similar to a backhanded compliment, MS fatigue might be perceived as a welcome cause compared to Alzheimer’s.
Nowhere did Preidt’s article ascribe mitigating circumstances. In that train-of-thought, nothing says there cannot be several and/or different “causes” for any condition. In fact, the cause(s) of MS is(are) still unknown. Plus, people with MS can also suffer from other diseases any person without MS can contract.
Our world is dynamic. New diseases seem to crop up from nowhere. Sadly, medicine is the performance of a search for cause-and-effect and subsequent treatment with many uncertainties.
The result: napping may contribute to or be a symptom of Alzheimer’s but it IS a symptom of multiple sclerosis.