Let me explain to you something extremely important about depression:

Your body put yourself in a state that is supposed to help you recover. That's exactly like some natural painkiller (hormones). Which reduce or remove any suffering. But it may act like some addictive drugs. When you start to recover, to be less tired, then your emotions start to function again, with all your sufferings awakening all at once. Because during anesthesia, the psychological pain doesn't stop. That's exactly the same as when you go to the dentist, and when the pain awaken because anesthesia doesn't work anymore. But instead of physical pain, this is mental pain. And that's when it can be dangerous: You get less tired, but pain also get stronger, whatever it may be. Emotions may overwhelm you in an incredible way. So much, that you may want the painkiller to be effective again. Which may push you to be hyperactive, in order to be exhausted, in order to appease yourself. That's the vicious circle of depression. But this also could be worse, as for some people, this awaking involves emotions flowing way too strong to be bearable, and may push someone to do something irreversible. If you're alone with your depression... ... well, I hope you'll find someone that may understand this fact, and helps you to recover and heal properly. But remember the pain is normal and natural, and that you must struggle to survive, like everyone who may have to struggle against something like this. And for people that have to support someone who's suffering from depression: be there for her or him ! Don't turn your back, and be strong to to help this person recover! Even if the person says "I am ok", be there ! Your presence and support may save a life !