[throwawaySG]

This study on Singaporean children (https://bjo.bmj.com/content/bjophthalmol/early/2021/04/14/bj...) says that

> Singaporean children had shorter reported time outdoors and lower light levels, relative to their counterparts overseas. In the current study, reported time outdoors was 1.7±1.6hours/day and average light levels were 458±228lux. In contrast, children of similar ages in Australia and the UK reported time outdoors of at least 2–3 hours/day.18 22 Likewise, higher average light levels of 1072 and 1627 lux were reported in Australian (age 10–15 years)16 and American (age 5–10 years) children,20 respectively. Differences in educational demands (homework load and afterschool enrichment classes),23 lifestyle and sociocultural factors may account for the lower reported time outdoors and light levels in Singaporean children

I can't remember exactly how many hours of exposure to sunlight the studies mentioned, but I think it was something like 2-3 hours --- and it might have to be more than just, e.g., being near a window. I'm Singaporean too, and that excerpt from that paper accords with my experience. I highly doubt that I and most of the people I grew up with had that much sunlight exposure per day.