The sinister howls of the werewolf have permeated folklore for centuries, but how much does this cosmic force really affect us? While more than 40 percent of hospital staff believe the lunar cycle can affect human behavior—and thus an increase in hospital visits—during full moons, research suggests otherwise. And while menstrual cycles can be highly variable, the moon cycles are always right on cue. There’s some potential here: our sleep cycles are very sensitive to and dependent on how much light we are exposed to at night, and what kind of light. Light pollution at night, which can be especially bright in urban areas, can disrupt our sleep cycles, research has found.