Matins Vigils · the Night Office
Keeping watchThe longest and most monastic hour, prayed in the dark while the world sleeps. Extended psalmody and long readings from Scripture and the Fathers (the lectio) — the soul keeping vigil, watching for the Bridegroom who comes at an unexpected hour.
In the modern Liturgy of the Hours this becomes the Office of Readings, which may be prayed at any time.