The word translated vigils is the noun derived from the verb "to watch" (in Hebrew shamor): both in the sense of "observe" and "guard." This word is used to describe the work of shepherds. The Lord is acting as the shepherd of his people. . . .

From Scripture we can see that when we keep vigil, we participate in 'watching' with God to protect our turbulent world from the forces of evil that are at work. . . .

If I were to keep a vigil what would I do? This format is for those who have what is sometimes called a rule of life and make vigils part of their everyday life. They wake at dawn with prayer, so they must rise before the sun and be present to the dawn. Since the purpose of this prayer is to ask for blessings for the day and to ward off evil spirits of the night, most practitioners take the hour before dawn in stillness. Some do centering prayer for thirty minutes, then do a lectio on a current book or experience. Somehow, it seems that our natural inclination is to do intercessory prayer as the sun rises. . . .

Another type of vigil is during an occasion of concern for another. From time to time we are called to pray intensely on behalf of another. This is the original meaning of a 'wake.' We stay awake and pray for another who may be dying or who is already dead. We can do this beside the bed, or the body. We can either dedicate an hour before we sleep or an hour in the middle of the night, or an hour before dawn: the method is to sit and center before an icon. Light a candle and lift up names in prayer as the Holy Spirit inspires you.

Mary Margaret Funk in Tools Matter for Practicing the Spiritual Life