Nyctophobia means a fear of the dark, but the speaker quickly makes clear that darkness is only part of the problem. What really frightens her is what happens inside her head: thoughts that keep her awake, follow her through the day, and make it hard to breathe. The nightlight is a small comfort, though she admits it can't switch off the paranoia.
The poem turns in the middle, when she calls the fear "a chain" rather than "just a phobia." Silence becomes unbearable too, and being alone feels like too much. In the last lines she drops her guard and describes herself as a "scared sad little girl" trying to run from the real world. The mood is raw, anxious and confessional. Short, plain lines make it feel like someone whispering the truth in the dark, with no polish or disguise. The poem ends without relief, which suggests how trapped she feels.