Why not make lightbulbs that produce the 350-400nm wavelength to stimulate/prevent eye elongation? I’m sure companies like Philips would love to sell you therapeutic LED bulbs at premium.
It’s probably the brightness, too. Outdoors during the day under a big tree is brighter than basically any indoor lighting you see outside a movie set.
Brighter, and not by a small amount. It's not entirely visible light, but insolation is roughly 1000 W per square meter at noon. I'm not sure I have 1000 W of bulbs in my entire house.
I read an interesting article by someone that set up "daylight" lighting in their home by essentially tiling their entire ceiling in high-efficiency LED panels. He offset the electricity costs using solar power and batteries.
The gist of it was that it very markedly improved the mood and general wellbeing of his entire family, and visitors would often comment about how "nice" his house was without being able to explain precisely why they felt that way.
Conversely, imaging living and working in a dark cave.
