Changing our understanding of infant colic.

C OLIC IS truly a noisy phenomenon in terms of the crying that the infant does. But it is also a noisy phenomenon to study in terms of the basic phenomenonology of crying that constitutes the defining behavioral feature of the syndrome. As can be appreciated in Figure 3 in the article by Clifford et al in this issue of the ARCHIVES, even at 3 months of age, after most colic has resolved, there is still a substantial range of minutes per week (or per day) of crying and fussing behavior. This is also true in the sixth week of life, when crying is usually manifest at its highest levels. In addition to the range of “individual differences” in levels of crying among infants, there is no single level of crying in early infancy that is normative. Indeed, the total number of minutes of daily distress manifest an nshaped pattern over the first 3 months or so of life: they begin to increase at about 2 weeks of age, peak during the sixth week, and then decline to under 1 h/d by 12 weeks of age. While this pattern is typical for groups of infants, individual infants may experience their maximum distress at earlier or later ages so that a single measure at a particular age may not capture the maximum for that infant (see Figure 2, Barr).