On Sat, 27 Jan 2018 16:38:50 -0800 (PST), RichA
wrote:
Circadian rhythm disruption. 90% of people in the civilized world
live in cities and most don't use pitch-black window blinds or
curtains.

Anyone who want to can get and use such curtains. It's much harder to
put a pitch black blanket over the whole city to get dark skies...
:-)