Major depressive disorder is a common and serious medical illness that negatively affects how you feel , the way you think and how you act. A certain level of stress can be useful, it helps us to learn coping skills and build resilience. However, if the feelings of irritability, sadness and hopelessness persist or are so intense that they interfere with normal life activities or you are unable to identify the cause of your stress and low mood then you may be suffering from depression.
People suffering from depression often show distorted thinking. Everything looks bleak to them, and they hold extremely negative views about themselves, their situation, and the future. Trapped in their pessimism, they brood/obsess over their problems and blow them out of proportion. Feeling hopeless and helpless, they may even start to see suicide as their only way out. In many cases, the first time someone becomes depressed, it has been triggered by an unwelcome or traumatic event, such as being sacked, divorced, or physically or sexually assaulted. Fortunately it is also treatable. By restoring serotonin (happiness producing Neurochemical) levels with the help of antidepressant and anxiolytics person can bounce back to normal level of functioning.