What experiments are those? I don't doubt if you lock someone in a room they'll lose sync with the sun, but people in society do rely on it. The fact that we use DST in the face of very vocal opposition shows a lot of people do care about it.

The existence of China as an outlier isn't much evidence. The most people on one side do not keep the same schedule as those on the other. If daylight really weren't an issue, there would be only one timezone for the entire Earth. So you can't point to one while ignoring the reason all of the others exist.