I did'nt want to add a page about this subject but I realised again how important it is and how it has massive impact and you can't see it coming and I will add more later. 

The Black Dog of Depression is a bastard.

What was initially a small phrase uttered to describe a brief period in a person's life, the metaphor has grown to encompass a spectrum of depression and its symptoms. For some, the metaphor of the black dog is effective because depression can feel like an ominous, long-suffering presence tracking your every move. This metaphor can represent the gradual overtaking of the things you once loved, the person you once recognized in the mirror, or the life you once lived. Depression does not take breaks but instead follows you around like a shadow – a large, lumbering shadow, loyal as a canine. At its inception, though, the black dog was not quite so insidious.

Depression, or depressive disorder, is a mood disorder, wherein the body and brain do not produce the "feel-good" chemicals required to control mood, sleep, normalizeappetite, and clear thoughts. Symptoms of depression include apathy, under or oversleeping, loss of interest in food, too great an interest in food, muscle weakness, thoughts of suicide* or despair, and irritability. Simply feeling momentary content might feel far from reach at times, or often.

These are just a few of the symptoms ascribed to depression, and they can all be either mild or severe or a patchwork of both.

Although periods of sadness, anger, or apathy are normal in people who have experienced a sudden loss, a traumatic event, or similar, persistent feelings of sadness, anger, and apathy – those that last at least two weeks– may be attributed to depression. Depression, or major depressive disorder, may initially be mild, but without treatment, symptoms can grow worse and develop into a chronic condition called  a depressive state that persists for at least two years

There are many possible reasons for depression, and there is still some mystery surrounding why it develops in some people and not in others, with similar risk factors in place. Minimizing risk factors is certainly worth the effort, though, and engaging in a healthy lifestyle can go a long way in mitigating some of the likelihood of developing a depressive disorder.

Who Does Depression Affect?

Depression is said to affect as many as 1 in 13 adults, though many will not seek treatment. Depression is more likely to affect individuals who are going through major changes, such as reaching adulthood, quitting, or starting a job, or losing a loved one. Depression is also more likely to affect individuals who do not have a solid support system and may be more common among people who have experienced significant breaks within familial or friendship ties.

Depression does not seem to have particular risk factors based on socioeconomic status, race, or religion, as people of all ages and backgrounds can experience the symptoms of depression. Across the board, depression requires some amount of treatment and should never be diagnosed or treated entirely at home. Instead, please seek out the assistance of professional, licensed mental health services.