You can apparently get by with very little light if you're happy with the moon seeping through the clouds when it's only a 17% crescent.
I've long thought I had better, or even much better, than average night vision...without even a shred of data to objectively support that belief--ha!
True or not, if there's good snow cover on the ground, I don't have any problems running on trails after dark during the winter, or skiing. At least as long as there isn't total cloud cover with very dense clouds. Last night would have been perfectly fine had there been no moon at all.