The amygdala is the area of the brain that facilitates emotional responses, such as pleasure and fear. In people with depression, the amygdala becomes enlarged and more active as a result of constant exposure to high levels of cortisol. An enlarged and hyperactive amygdala, along with abnormal activity in other parts of the brain, can result in disturbances in sleep and activity patterns.

It can cause the body to release variable amounts of hormones and other chemicals in the body, leading to further complications. Depression has the potential to damage the brain. The person can have difficulties remembering and concentrating. It can also lead to a poor attitude, negative thinking and behavior.

Researchers have discovered sadness does impact the human brain. Two areas of the brain showed increased activity when feelings of sadness were experienced by subjects being tested. One area is known as the prefrontal cortex, specifically the left side, and the second area, contains structures of the limbic system near the face. This increased activity could be seen with brain imaging technology known as positron emission tomography.

It is interesting to note that the left prefrontal cortex “gets more active during ordinary sadness, but shuts down in people with clinical depression. Perhaps the left prefrontal cortex somehow burns itself out when sadness persists for several months."