[the8472]

> 2. Would it actually matter if there is also light outside this band?

Your pupils will adjust to perceived intensity. So if the bulk of the light comes in at shorter wavelengths it'll contract and you'll get even less of the already small fraction in the range of interest.

On the other side in the infrared it's more a question of safety. You don't want to overload your retina.

So you want it visible but long wavelengths only, which boils down to a fairly narrow range.

That's assuming it actually works. Single studies and all that.