I go through these stretches of time where I feel extremely empty (like I’m not a person inside) and it makes me feel worthless, hopeless, helpless, agony, apathy, and want to die. 

My current therapist says he thinks this state is caused by repressed emotions. I've told him it can be triggered but it can also just come out of nowhere. And it always disappears out of nowhere - with no change to feelings, circumstances, or thoughts. He says nothing that happens in the brain happens out of nowhere. I told him I tend to just wake up in that state or an okay state. He said maybe it happens in the dreams.

If you experience this state, what do you think the root cause is? Do you think treatment can keep it from happening? If you used to experience this state and no longer do, what do you attribute to remission of this symptom?