I live in Northern Europe and in this time of years it is not uncommon to have cloudy days with little light (you need lights on indoors) for weeks at a time. I wonder people from before artificial lighting had adaptions to lower light levels.
Not necessarily contradicting this, but even overcast days still have a high amount of sunlight outside. We don't really notice the difference to room lighting because our eyes have a very high dynamic range, but during the day (unless you live in the polar circle), the intensity of sunlight outside (and also the broadness of its spectrum) are much higher than any common indoor lighting.
Living in Scandinavia has really made me hate the kind of studies. You have stupid advise like "Get up early and get sun in your eyes first thing in the morning"... Okay so which is it, sleep til' 9:00 or get up early, in the dark? It's the same with, go to bed when it's dark, right now the sun set at 15:40.
If the suggestion is that I reduce my working hours drastically during the winter I'm all for it, but it is getting a little tiresome that supposed scientists completely ignore the fact that a pretty sizeable chunk of the worlds population lives pretty far north and have done so for thousands of years.
The research may very well be right, but it's not particularly useful if you don't address the fact billions of people live in areas where you're recommendation don't make sense.
When I was preparing for a trip south, I noticed that the southernmost city (according to itself), Ushuaia is south of 54 degrees latitude, while Copenhagen is nothing like the northernmost city yet is about 55 degrees north.
This is a way of amplifying that plenty of people live north of other people. Whole countries.
This is definitely not as black and white as you put it.
Today, where I live (53 degrees latitude, northern hemisphere), the brightest point of the day is just about 100W/m². That converts to about 12000 lumens, but that is only at the very brightest midday hour. Before that or after that, it is only about a third of that. There are plenty of days where it doesn't even reach 100W/m².
On those days, daylight is more dim than regular lamps even at the brightest point of during the middle of the day.
