[Lotus Eater]

It's always hard to be completely sure because the 'symptoms' could be caused by other sicknesses and such but.. you will know when it gets really hard to wake up in the mornings knowing that you have to get through the rest of the day. When things you once found fun and interesting are suddenly the biggest bore. When nothing makes you smile the way it used to before. When even the littlest of actions wear you out. When you start doing harmful things to 'escape'. When you're always looking for some form of release. When you're left feeling really emotionally drained all the time. Sometimes, all you want to do is cry. And there isn't always a reason. If you're getting suicidal thoughts/hurting yourself or the people around you or feel as though your brain's about to explode with all the stress and anxiety, it is time to get yourself to a doctor immediately.

That said, you could go to the doctor as soon as you start feeling depressed. It's always better to get in early.. They do help you in their way and it will cut down on all those days/months of simply waiting for times to get 'bad enough'.

Hope this helps :/