Compline is one of the 8 services for the day in the Catholic “Liturgy of the Hours”. It was added to the Episcopal Prayer book in 1979
Compline is a service to close the day, an opportunity to give thanks for the joys and graces experienced, a chance to confess the (many) sins committed throughout the day, and the perfect moment to close the day the same way it started: in prayer and asking for God’s protection during the night to come. It is descended from the night prayers said before bed at the end of the monastic round of daily prayer and can be traced back to the 4th century and referenced by St. Benedict, St. Basil, and St. John Chrysostom.
St. Benedict had this to say about the simplicity of Compline: “Let Compline be limited to the saying of three psalms, which are to be said straightforwardly without antiphons, after which let there be the hymn of that hour, a lesson, a versicle, the Kyrie, and a blessing to conclude.”