It is believed that crying when sad is a physiological way for the body to release stress. It also may be a way for the body to signal a need. Such needs may be internal or external.
Like laughing, crying is largely involuntary and somewhat social. Those who cry in public often receive sympathy from those around them. Crying is also therapeutic. A large amount of research subjects report feeling better after they cry.
Although statistically, some people cry more easily than others, scientists are not sure why. People who experience trauma tend to make up a portion of those who cry easily, though trauma is not exclusively the reason. Gender also plays a role, as women tend to cry more easily than men. Scientists believe, however, that women cry more easily because it is more socially acceptable, as women do not have a biochemical tendency to cry more easily than men.
Although experts say that it is okay to put off crying until an individual is in a time and place where doing so is more acceptable, they do not recommend avoiding crying altogether. Preventing oneself from crying may result in emotional flattening as well as physical problems within the body.