Here the speaker describes a kind of tiredness that has nothing to do with physical effort. They can spend a whole day doing nothing and still feel worn out, and even thinking is draining. Then night comes and sleep won't come with it, so the exhaustion has nowhere to go.
The central image is a hole: an endless fall into an abyss. What stands out is how little there is in it. No task, no destination, not even a bed to lie on and think things over. The repeated "nothing" and "nowhere" make the speaker's world feel stripped down to bare space. The casual voice, with its lowercase letters and the offhand "kinda," makes the despair feel quieter and more real, as if the speaker is too drained to dress it up. The final line states the feeling flatly, and the mood is heavy, numb, and lonely. The poem doesn't offer comfort or a way out.