It never reaches the ground. The brightness of the night sky is due primarily to direct uplight, not light reflecting off the ground. Uplight should not be tolerated. Light fixtures which produce no uplight, called full-cutoff, are readily available. The human eye naturally adapts to a lower light level at night than in the daytime.
Visual performance is excellent at lower light levels, especially when glare is eliminated.
Their comprehensive and ongoing testing has shown what light levels are best. Lighting should not exceed these recommended levels . Overlighting provides no benefit, wastes energy, and lessens visual performance by increasing discomfort glare and disability glare. It also makes less-well lit areas seem darker, because night vision is destroyed. It also occurs when we use inefficient light sources.