The lullaby apparently has always been a little bit of fear-mongering and a little bit of love. Four millennia ago an ancient Babylonian wrote down a lullaby sung by a mother to her child. It may have got the baby to sleep, but its message is far from soothing - and this remains a feature of many lullabies sung around the world today.

The lullaby evokes a variety of functions: song of love and praise toward the child, song to lighten the work of parenting, magical incantation that increases the sense of the parent's control and invokes sleep in the baby, or outlet for the adult's difficulties to a listener who does not understand the words (Trehub & Trainor, 1998). Farber (1990 in Trehub & Trainor, 1998) describes Babylonian and Assyrian lullabies dating from the first century BC that say babies' tears disturb the divine order.

But in all likelihood, the primary and concrete function of the lullaby is to calm or induce sleep in the baby. In comparison, the objectives of play songs are more didactic (e.g., learning alphabetical or numerical sequences) and have the benefit of stimulating the young child. Schore (1994) considers that parental singing permits a gradual increase of the tolerance to the affective tension, a major developmental task in the first year of life, and that this leads to an increased tolerance of intense positive affects of joy and excitement typical of the age in which the child becomes mobile and visual contact becomes the primary way of connecting with the mother.