I hope I am a good person but it is often the good-hearted ones who suffer from depression. As you say, we absorb the pain of others, singularly and collectively. Genetics, too — my mother, whom I never knew, suffered from anxiety and I assume depression. I know she was one of the first patients for shock therapy for her anxiety. My sister believed our mother’s heart was weakened in those shock sessions, leading to her death from a heart attack at 39.
I rarely feel rested, even now when I don’t consider myself depressed. When I was clinically depressed, the fatigue was like a wet blanket, all day, every day.