Our family always went to Midnight Mass. I'm sure there were times we didn't but all my memories of Christmas include that cold trek to St. Cecilia parish in the dark. It was magical, and sure as a child my thoughts weren't always focused on the right thing, but still, the incense, the darkened church, the choir singing beforehand, the placing of the baby Jesus in the manger, all created a holy atmosphere.
Pope Sixtus III around 430 A.D. instituted the midnight Mass for the Catholic Church. It is the earliest we can celebrate the actual Nativity of the Lord. As one of the of six Feasts with a designated vigil, Christmas enjoys rare standing in that there are four Masses, (Vigil, Midnight, Dawn and Day) that may be celebrated. Because feasts were such special, holy days, Vigil Masses, a Mass of anticipation were instituted, but the texts, the readings, the prayers were all still in the mode of anticipation, the event of the feast had not happened yet.
Midnight Mass is different, just look at the responsorial psalm "Today is born our Savior Christ the Lord" The Response at the Vigil? "Forever I will sing the Goodness of the Lord" and get this, the Gospel Acclamation? "Tomorrow the wickedness of the Earth will be destroyed, the savior of the world will reign over us" At Midnight? from Luke 2:10-11 "I proclaim to you good news of great joy, today a Savior is born for us, Christ the Lord".
What is your point you are thinking to yourself... Well it's this. around 14 years ago we moved, and began attending a new parish. And we went to Midnight Mass - at 10 p.m. 10 p.m., the same midnight Mass readings and prayers all about Today Today Today, and yet It was really going to happen tomorrow! I just don't get it, a vigil is a vigil, it is anticipatory, but Midnight Mass is not. Ok, so it is just one parish no biggie. But get this- it has apparently become so widespread that even the USCCB website, and Liturgical materials from OCP (see picture below) now call it "Mass during the Night"
Thankfully the parish we moved to reverted several years ago back to Midnight for the (go figure) Midnight Mass. I'm just a layman, no theology degree, but how can it be the "Mass during the Night" when the liturgy itself is so obviously about Christmas day and not in anticipation of Christmas day.