The Night Hours are the fixed times of prayer in the Divine Office of the Roman Catholic Church, that take place after sunset and before sunrise. In the Latin Rite, the main Office is traditionally Matins, said in the early hours of the morning, and which is joined to the office of Lauds, which is concluded shortly before dawn. Vespers, traditionally said just after sunset, and Compline, said immediately before retiring to bed, are also sometimes considered to be part of the Night Hours. The Eastern Christian Churches, including both Eastern Catholic and Eastern Orthodox Churches, have a similar structure of night prayer, but the terminology is usually different. Some Protestant communities have similar prayer times.
The contents of these prayer offices vary greatly with season, day of week, and feast days, which is unlike the Daytime Hours, which tend to be invariable. The offices consist of a hymn, psalms and canticles with antiphons, versicles, readings from scripture, Fathers of the Church, Councils of the Church, lives of the Saints, etc., and specific prayers.
Latin Rite Catholic usage
The office of Matins is the longest of the daily offices, and includes a minimum of two lengthy readings, and traditionally had the most number of psalms and canticles. Since the reforms that followed the Second Vatican Council, the Liturgy of the Hours has renamed "Matins" as "Office of Readings", allowing it to be said at any time during the day or night. The Office of Readings has only three psalms or portions of psalms, where the earlier form had nine, and two readings, in length similar to the total length of the readings in the three "nocturns" of the previous form. Clergy who have an obligation to celebrate the Liturgy of the Hours may still fulfil their obligation by using the Roman Breviary promulgated by Pope John XXIII in 1962. A characteristic of Matins or the Office of Readings, is the ancient hymn, Te Deum, said on Sundays and solemnities.
The office of Lauds, traditionally said just before sunrise, is now often called, in English, "Morning Prayer", though the official name (in Latin) remains unchanged. The character of this office is one of praise to God.
The office of Vespers, traditionally said just after sunset, has been renamed "Evening Prayer" after the Second Vatican Council, and is to be said at about 6 p.m. The character of this office is one of thanksgiving.
The office of Compline, is said just before retiring to bed, and has been renamed "Night Prayer" after the Second Vatican Council. The character of this office is a meditation on death.