While feeling sad from time to time is a normal human emotion, sadness that lasts for an extended period of time can be a symptom of depression. Depression is a dangerous disorder that can negatively affect your life and even lead to fatal consequences. The major signs of depression are:

-Sadness for most of the day that lasts for more than two weeks
-Feelings of hopelessness, intense guilt or worthlessness
-Feeling that your family or friends would be better off without you
-Weight loss or gain that is unintended
-Inability to focus or concentrate on a task
-Becoming irritable, aggressive or short-tempered
-Engaging in reckless behavior 
-Becoming sexually promiscuous or disinterested in sexual activity, erectile dysfunction
-Feeling suicidal

People who are suffering from depression may experience it in a number of forms. Seasonal affective disorder affects people primarily during the winter months when the weather is colder and there is less mood-enhancing sunlight. Bipolar disorder afflicts the sufferer with manic highs and devastating lows, making them go from feeling either extremely happy and excited to hopeless with no middle ground. Bipolar depression can lead to binge eating, spending sprees, impulsive and erratic behavior on one end of the spectrum and suicidal negative thoughts on the other. 

Mothers suffering from postpartum depression may become sad, fatigued and suffer a loss of interest in daily living activities. Many women suffer from insomnia, frequent crying spells and may even have suicidal thoughts. They may become unable to care for the baby and detached from their family. Postpartum depression can become increasingly worse with subsequent pregnancies, so women suffering from these symptoms should seek treatment immediately. A combination of psychotherapy and antidepressants is often helpful in treating the symptoms of postpartum depression. 

For most depression sufferers, the disorder is triggered by an event or series of events that overwhelm the person. A job loss, death of a loved one, humiliation, divorce, loss of a significant relationship or major illness may all cause depression. Some people, however, suffer ongoing depression for no apparent reason. This depression may start in adolescence and continue throughout adulthood. 

Dysthymia refers to a condition in which a person has a consistently low mood but is not as sever as major depressive disorder. Major depressive disorder is a debilitating condition. It can prevent the sufferer from being able to form healthy relationships, maintain employment or earn a living and can even cause destructive behavior that leads to death. 

People who suffer from depression find many ways to cope with the sad feelings and depressed mood that accompanies the disorder. Some of these coping mechanisms can be dangerous such as alcohol abuse and binge eating which leads to weight gain. Others turn to drugs and may become unable to carry on normal daily functions such as maintaining hygiene, working at a job or caring for family members. There is hope for depression sufferers. With psychotherapy and antidepressants, depression can be treated and cured.