Given the wonders of dark adaptation of the human eye (https://en.wikipedia.org/wiki/Adaptation_(eye)#Dark_adaptati...), does that really matter? In my experience, the full moon is almost bright enough to comfortably read normal black on white printed text.
Many of the mechanisms for light impacting biological functions show a clear dose-response relationship - fewer photons hitting the retina leads to less effect.
As a rough estimate, one decade (10x) of the eye’s light adaptation, at most, comes from aperture variation - the pupil expanding and contracting. The rest comes from intensity-driven modification of the sensing and image processing systems in the eye - rods that are completely saturated with signal above a few dozen lux become the primary sensors in very low light.
In other words - just because the moon provides enough light to see and even read doesn’t mean that it will cause insomnia.
As a rough estimate, one decade (10x) of the eye’s light adaptation, at most, comes from aperture variation - the pupil expanding and contracting. The rest comes from intensity-driven modification of the sensing and image processing systems in the eye - rods that are completely saturated with signal above a few dozen lux become the primary sensors in very low light.
In other words - just because the moon provides enough light to see and even read doesn’t mean that it will cause insomnia.