You are not alone, I've fought a similar battle. I didn't recognize it as depression.  I just got fatter,lazier, angrier, irritable, very defensive, lots of negative behavior.  I've worked very hard to over come most of my problems.  I have days that are similar to yours, my creativity and motivation are almost gone.  I deal with the illness by taking medication, using therapy, making new friends, it is very easy to crawl back into bed and sleep all day.   Believe me I do it faster than a jack rabbit can run.  I don't know the answer to the effects of depression.  For me it helps to reach out and get busy, I've lost weight, feel better.  Decision making is much easier, handling my day to day affairs is 100 % improved.  Reading self help books has been a God send.  I'm learning to take care of me first instead of the rest of the world.  I think that is the trick to recovery.

France