Keeping vigil has always been a spiritual practice in Catholicism. This is what we are essentially doing by attending any “Vigil” mass, we wait in joyful hope for the coming of the Savior.
There is also a Biblical reference here that can be included. The Shepherds in Luke’s infancy narratives in his Gospel were keeping watch over their sheep on the nightly vigil. In a sense, we are the same shepherds today and we are entrusted to keep watch over one another.