Cosmoline,
When you are talking about a massive output of lumens into dark adapted eyes, it will work on bears as well as they do on humans.
It is the same as when you approach a deer in the road in your car, and they stay put and don't move, it is because they are blinded and because they can not see they don't move.
It is the same technique than the poachers use, to blind them with a spotlight so they can shoot at leisure.
I have spotlighted a lot of black bears when the dumps of Minerva and Newcomb in the Adirondacks were open at night (years ago) I was doing research and observing trends. I knew they could not see even when appeared that they were looking at the light, because my assistant could move close to then by flanking.
If the wind was proper my assistant could get close to them, two senses were negated to them, one the sight and another was the scent, (as the wind didn't help them) of course we had to be careful as they could still hear very well.
So a very strong light will help to blind them and for you to see your sights and your target.
It will not help you during the day
black bear