Some people get diagnosed as depressed, the reasons might be various, some people get depressed because of their insomnia some people for other reasons, but honestly I don't think anyone can be depressed not even once. They are going through moments that are not the ones that you'd expect and you get in return unsatisfactory feelings hence you are not happy, some people go to the doctor to cure this state of mind, but doctors have no clue of what they are doing because they don't know what's roaming into your head and they are just believing everything you say and based on the canonical answers you give to them they are telling you: depressed or not depressed. I deeply think that the way it works right now is very stupid and maybe only 1% of the doctors out there can have a fraction of the power to prescribe to you drugs that are completely lethal for you, it's so retarded that police spend money and time to follow people who sell drugs such as ecstasy , marijuana, heroin etc. when the drugs that are prescribed by a doctor are legal and allowed to take them. I was always the skeptic on the traditional medicine and I was always sure that they were all a bunch of drugs used to feed the pharmaceutical industries and not to actually helping you.
So whenever you feel "depressed" the first thing you want to do is to change something in your life, unhappiness and depression are caused to something that goes wrong, EXCUSES ARE THE ROOT of the depression, there are no excuses to get happiness. These feelings are working exactly the same as the external precautions sensors we have, for example, if you want to touch a fire we know that this will hurt us because we have experienced hurt from touching it sometimes during our life, the same are working the mental safety our brain is creating, like if your dating the wrong person your body will react with depression and unhappiness and will put you in a circumstance of awareness that you need to get rid off that person. So before believing in a doctor put up a dotted list on things that are bothering you and day after day get rid off these things and or change them at least (examples):
Anyone on earth is designed to be healthy and happy, if we are not, nothing else introduced in our body can help us to be better persons, questioning ourselves constantly and thinking that everything is possible will save you.