Well... honestly I don't know the answer to this. But I'm familiar with the experience. It's something I've struggled with pretty-much all of my adult life. In my case, I've always struggled with a lot of social anxiety in particular along with more generalized anxiety & depression. And I most unwisely always managed to end up working in jobs that required a high degree of professional interaction. So I was pretty-much always stressed out to the max by the time I would get home in the evening. As a result, I was always worn out both emotionally & physically. Any kind of interaction with family members or anyone else was a struggle. I just wanted to be left alone.

Over time I think that living this way my body gradually reached a point where it no longer knew how to function any other way. So even today, now that I'm retired & mostly reclusive I still function the same way. Perhaps what you're experiencing is also a reaction to anxiety? I clearly don't know. But this is what happened with me. The other possibility, though, could I suppose be that you have something going on physiologically that is draining your energy. It might be worth getting yourself thoroughly checked out medically, perhaps including a consultation with an endocrinologist? If that doesn't produce anything substantive, then perhaps some mental health services are the other thing to consider. I wish you well...