Science often misapplies clinical / lab data over the real world. That's why the results of so many clinical trials fail to manifest in real-world, free living subjects. It's also why more "intervention" trials are pointing to benefits that clinicals miss.

The question in this case it why these suggested impacts of the twice/year time changes, where you lose or gain just 1 hour, don't also manifest whenever such time changes are encountered as part of normal day to day life or self-induced, such as a vacation into another time zone.

My sense it that, as is often the case with such data collection, the psychology greatly impact the physiology. We human tend to resist change....unless it is change that we want to occur. The physiology remains pretty constant while the psychology is quite different.