Babies cry primarily as a form of basic instinctive communication to express their needs or discomfort. Common reasons why babies cry include hunger, sleepiness, needing a diaper change, gas pain, discomfort from temperature or clothing, loneliness, overstimulation, and pain such as from teething or illness. Sometimes babies cry for no apparent reason or as part of colic, which is prolonged crying without an obvious cause. Crying is also a way for babies to feel comforted and secure when they are close to their caregivers. It is normal for babies to cry for about 1 to 3 hours a day, especially peaking around 4 to 8 weeks old, and gradually decreasing after that. Babies have not yet developed other ways to express their needs and emotions, so crying is their primary form of communication and self-soothing is limited. Parents and caregivers respond to crying by trying to identify and meet the baby's needs, for example by feeding, changing, comforting, or soothing them through holding or gentle motion.