lullaby  Tag

From Wikipedia:

A lullaby, or cradle song, is a soothing song or piece of music that is usually played for (or sung to) children. The purposes of lullabies vary. In some societies they are used to pass down cultural knowledge or tradition. [..] Perhaps one of the most important uses of lullabies is as a sleep aid for infants. As a result, the music is often simple and repetitive.