It's almost certainly a reality that everyone has at a moment or two felt depressed like being gloomy or upset. Even those who constantly seem to be happy and smiling do get these signs. Bu this does not necessarily mean that they are afflicted with the actual clinical malady. The real indications of depression have to be understood properly, diagnosed and treated properly.
The warning signs of depression are somewhat similar to other forms of emotional suffering. The disparity is that the other forms can be pinned down to a specific problem, like the grieving over someone's passing away, which may cause one to be upset or sad and be depressed for a long time. These signs tend to go away and can not be considered to be the real signs of depression unless they last for more than a year or so and does severely hamper their everyday work. Grieving over the loss of a near and dear one is only normal and can be expected and can last even a lifetime as long as it does not get so crushing that it affects their work and their relationship with others as time goes by. If so it is serious.
The symptoms of depression can be gauged by the intensity of one's sadness and the constancy of it. Even a bad day can cause a severe case of blues for just about any and everyone, but a good night's sleep or quality time spent with family or friends can dispel it away the next morning. Even inclement weather effects some people sometimes, but once the bad weather is over the person gingers up and is back to his own self. But when this "blue" feeling gets bad and the apparent symptoms of depression last for an uncommon length of time, then they become the true symptoms of depression. Clear clinical depression can be identified with a feeling of emptiness, a loss of purpose in life, even hobbies and other activities once enjoyed seem dull, and also in finding it difficult to relate with friends and family. It does not always lead to suicide but to a lack of self respect. The indications of depression differ from one person to another but in common they are apt to dislocate normal life. While "Monday Blues" is a common occurrence, for these depressed people, it is always the blues, even getting out of bed.
You should realize that it is time to consult your physician the moment you find out that your symptoms of depression are getting out off hand so far as to interfere with your work or life or if you are falling back in your responsibilities to your family. If left untreated, the signs of depression become worse and will come to a head at such time that it will be extremely difficult for even medical help to be of any use. If you feel that you are having symptoms of depression, talk it over with your family physician and get the help you richly deserve.