As someone who worked nightshift for 18 years I really think it does at least help sleep wise. I blocked Blue light a few hours before I want to sleep and when waking I'd use a sad/sun light when waking up.
I don't do it now but I'm convinced that's one of the reasons I managed it for so long.
Basically I'm saying blue light wakes you up and helps set your body clock but avoiding blue light for a while helps you sleep. I was never aware of any claims blue light is unhealthy but I guess it makes sense as you could argue the sun itself is bad for you.
Yes and that behavior is actually pretty well researched. There is a specific band which will result in the brain not getting into "sleep mode" sloppy said.
But there is no scientific proof that it is damaging to your eyes or harming your health in any other way.