I wonder is this impinging on cultural norms to the point to where our own explanation totally misses the POV that the traditions dictates...
the explanation seems plausible of course given the effect dreamlike state has on our body's vitals (increasing hr/bp/stomach acid amongst other things) but to simply call it a nocebo...I'm not particularly sure because it sorta makes it seem like their fears aren't realistic to a degree where sleep is something we've barely scratched the surface of in western medical research.
The correlations found are unique I do admit and the study's aims are admirable, and without getting into a relativist argument I can say it seems sound save from my initial criticism. I guess instead of having one explanation, there are now two?