Sadness

Sadness is an emotion characterized by feelings of disadvantage, loss, helplessness, sorrow, and rage. When sad, people often become outspoken, less energetic, and emotional.

Sadness can be viewed as a temporary lowering of mood, whereas depression is characterized by a persistent and intense lowered mood, as well as disruption to one's ability to function in day to day matters.

Medicalization
Sadness is an unpleasant emotion that has been medicalized. People who express sadness, such as after the death of a parent or child, are often told that they should seek medical care rather than being reassured that it is a normal response to loss.

Pupil empathy
Facial expressions of sadness with small pupils are judged significantly more intensely sad with decreasing pupil size. A person's own pupil size also mirrors this with them being smaller when viewing sad faces with small pupils. No parallel effect exists when people look at neutral, happy or angry expressions. The greater degree to which a person's pupils mirror another predicts a person's greater score on empathy.