Aspartame may well be nasty stuff, and I avoid it just as I avoid a lot of other stuff -- why put strange chemicals in your body when they have no real purpose? I used to be a Diet Coke
junkie (used partly to counter my [Lyme] fatigue), but I gave it up and am glad I did.
However let's not get correlation mixed up with causality. Meaning: If I happen to oversleep on a day when it later rains, my oversleeping did not CAUSE the rain: it was a coincidence.