Almost all babies go through a fussy period. When crying lasts for longer than about three hours a day and is not caused by a medical problem (such as a hernia or infection), it is called colic. This phenomenon occurs in almost all babies. The only thing that differs is the degree.

Colic usually strikes toward the end of a long day, when your baby is just about at the age when your sleep deprivation has really begun to set in. Your baby stops being the quiet, peaceful, miracle baby and begins screaming every evening. It is no wonder that parents can become frustrated, discouraged, and depressed.

The child with colic tends to be unusually sensitive to stimulation. Some babies experience greater discomfort from intestinal gas. Some cry from hunger, others from overfeeding. Some breastfed babies are intolerant of foods in their mothers' diets. Some bottle-fed babies are intolerant of the proteins in formula. Fear, frustration, or even excitement can lead to abdominal discomfort and colic. When other people around them are worried, anxious, or depressed, babies may cry more, which in turn makes those around them even more worried, anxious, or depressed.

About 20% of babies cry enough to meet the definition of colic. The timing varies, but colic usually affects babies beginning at about 3 weeks of age and peaking somewhere between 4-6 weeks of age.

Colic will not last forever! After about 6 weeks of age, it usually begins improving, slowly but surely, and is generally gone by 12 weeks of age. When colic is still going strong at 12 weeks, it's important to consider another diagnosis (such as reflux).