Humans have circadian rhythms that have health effects:
* https://en.wikipedia.org/wiki/Chronobiology
See my comment linking to various position papers of the scientists who study in this field:
* https://news.ycombinator.com/item?id=26088541
They generally want to get rid of DST completely and stick with Standard ("winter") Time all year round. (I don't know enough to gainsay them.)