Hi GG -- As I understand, stress is the result of adrenalin and similar biochemicals flooding the system. Humans developed the "fight or flight" response to fear/danger so that the body would get a chemical boost to fight that woolly mammoth or run like the dickens.

Today, the fear/dangers we encounter do not require us to respond physically. Yet, the system is still flooded with these chemicals that rev us up for battle or speedy retreat.

Short answer: yes, both stress and depression can cause/contribute to exhaustion.

So sorry you are feeling used up.

I seem to fight a perpetual cycle of not being able to sleep, pulling myself out of bed by a reasonable morning hour so that I don't sleep half the day away; then wind up exhausted til afternoon; work; and can't get to sleep. . . . .