> I think you're missing the parent's point.

I'm not missing the point: the various various folks who study sleep and chronobiology would have (I hope) reviewed all the literature, including studies that cover northern Europe, before coming to their all-year Standard Time conclusion.

A position paper from Society for Research on Biological Rhythms (SRBR) in Journal of Biological Rhythms cites Russian data for example:

> Borisenkov MF, Tserne TA, Panev AS, Kuznetsova ES, Petrova NB, Timonin VD, Kolomeichuk SN, Vinogradova IA, Kovyazina MS, Khokhlov NA, et al. (2017) Seven-year survey of sleep timing in Russian children and adolescents: chronic 1-h forward transition of social clock is associated with increased social jetlag and winter pattern of mood seasonality. Biol Rhythm Res 3–12.

* https://journals.sagepub.com/doi/full/10.1177/07487304198541...

Last time I checked a map (parts/lots of) Russia is just as north as Finland, Sweden, and Norway, and still the Russian government decided to rollback all-year DST.

Perhaps the effects differ in magnitude depending on geographic region, but as a general rule all-year Standard Time appears to be the best policy for most people most of the time.