What is depression?

We all go through ups and downs in our mood. Sadness is a normal reaction to life’s struggles, setbacks, and disappointments. Many people use the word “depression” to explain these kinds of feelings, but depression is much more than just sadness.

Some people describe depression as “living in a black hole” or having a feeling of impending doom. However, some depressed people don't feel sad at all—instead, they feel lifeless, empty, and apathetic.

Whatever the symptoms, depression is different from normal sadness in that it engulfs your day-to-day life, interfering with your ability to work, study, eat, sleep, and have fun. The feelings of helplessness, hopelessness, and worthlessness are intense and unrelenting, with little, if any, relief.

Hi,
I think that depression could be described as an extrene form of pessimism, obviously you're more likely to be sad when you're pessimistic because sadness is a measure of how much worse than usual you expect the future to be, but I suppose that at some point you could get so used to expecting a bad future that it no longer seems worse than usual.
Lots of hugs