Darwin suggested that humans' innate fear of darkness is an adaptation for avoiding predation by nocturnal predators. And, at least in the case of lions, it seems he was on to something.
Studies of African lions have found that the darker the evening, the more hunting success lions had and the more food they consumed.
But, contrary to what might be expected, that doesn't mean that dark, new-moon nights are when you should avoid going on safari. Humans are actually most likely to be attacked during the first week after full moon, when it's still more than half-full.
That's probably because the first hours of the night are darkest during the week following full moon—the moon rises at least an hour after sunset. That happens to correlate with the part of the evening that humans are usually outdoors and vulnerable. And the lions are hungriest at that time because of their low predation success during full moon nights.
As that study dramatically concludes, then, "The full moon is not dangerous in itself but is instead a portent of the darkness to come."