Fluorescent tubes are among the worst offenders for messing with my concentration, though anything with a pronounced 50 Hz flicker or too high a colour temperature isn't great for me. The kind of cheap lights offices traditionally use are particularly bad which is part of why I'm full time WFH now!
I won't cite, but only because i don't have a way to index my personal PDF repository, but the common consensus among people who study such things is that anyone living above the 20th parallel (or below, technically) absolutely must supplement vitamin D3, as even a full day in the sun naked is not enough to synthesize the amount of D3 we need.
So with that in mind, I'd honestly expect more people to know this and be supplementing D3. I don't have any specific recommendations, but i do know some guidelines and recent discoveries into "max dosing", so here they are. Anecdotally, i take 5000-6000iu every two days. I have a weird sleeping schedule so i really only notice "a day" as the sort of fog and fatigue i get after having gone more than 30 hours without D3. Prior to about 2015 or so, the max dosage was in the sub-5000iu range, with most supplement's labels stating that 500-1000iu was the "RDA" for D3.
However since covid was exponentially responsible for research into literally anything that could help alleviate symptoms/the disease and accelerate the time to recovery, some doctors were giving extremely high iu, up to 250,000iu over the course of a few days, or single doses of 50,000-80,000iu, with no deleterious effects reported.
Personally, unless i actually get sick, i try to stay under 8000-10000iu, at least until someone does a longitudinal study about the long term effects of doses higher than that.
As to the article and your point about lights helping - i've never noticed anything about any sort of light. I can feel awful at noon on a clear day while outside, or awful inside under every light type imaginable. I'm glad that light (and types of lights) help some people. I just think that the root cause is D3 deficiency, and no amount of 20k lumen arrays is really going to help.
As a quick aside, if you want to supplement children with D3 i recommend finding chewable d3 or a childrens multi-vitamin with omega-3/6 fatty acids. A couple of studies (with decent N and correlations) showed that merely supplementing omegas in children's diets improved the relationship and overall wellbeing of the children's parents - you read me right, parents didn't have to supplement to get the benefits of the children supplementing.
I've always been wary of going up to max-dose levels for that reason.
as mentioned though, i only think that 500-1000iu is not enough for most people. I'm not a doctor though, but it is one avenue of alleviating SAD as well as lethargy and stuff that most people vape/smoke/caffeinate to deal with.
It's a good idea to get your vitamin D status tested yearly and aim to be at least 50 ng/ml (120 nmol/l), but not more than 80 ng/ml (200 nmol/l).
As an example for dosages: I take about 7000 IU of vitamin D3 and 180 mcg of vitamin K2 daily. My levels test at about 180 nmol/l and my blood calcium is normal.
It may also be worth adjusting dosage between winter and summer months, depending on the amount of outdoor activity you do.
edit: it could be 25th or 30th, i have a hard time finding a single paper amongst thousands, either way it includes 90% of the population of the US, regardless of what parallel.
The lamp helped for a while but the suicidal urges kept creeping back over the years, until I finally moved back south. The urge to kill myself has pretty much entirely vanished now.
There is, I suspect, no one single cure for seasonal depression. Lights help, massive D3 doses help, vacations in sunnier places help, and there’s probably a ton of other biological factors helped by me living in the sunny place I grew up in versus Seattle.