Hello, DAICY!
Speculation: Your mind is protecting itself from itself, much the same as a person in extreme pain passes out.

My personal experience of depression is marked by persistent apathy. Part of it is probably medication-induced, but perhaps much of the apathy is a kind of psychological defense against painful thoughts and despair.

I don't know if this is the truth, and, if it is, I don't know whether it is ultimately good or bad. Maybe the apathy keeps me from a worse darkness, but it certainly has undermined my ability to function normally.

I hope others here will offer you different perspectives.