According to your description, the pre-sleep stage you mentioned is probably earlier than the shallow sleep stage in most cases, that is to say, the individual has not entered the sleep state, that is to say, the individual's EEG state has not changed, and it still stays at the low-frequency alpha wave frequency.
Now from the information you gave, I guess you suspect that the current situation is caused by reading Interpretation of Dreams, and you think that temporary insomnia is caused by excessive unintentional attention.
Next, let's analyze, for the average person, do you have any memories or experiences of certain things and certain appearances before going to bed? I think, even if you haven't seen Interpretation of Dreams, you will still remember something before going to bed!
At present, insomnia is mostly caused by anxiety or physiological reasons, and the mechanism is still unclear. According to some conclusions now, you are likely to be in an anxious state, so that you can't sleep, or even wake up when you fall asleep. In other words, unintentional attention is probably the premise of anxiety, which is different from intentional insomnia. The latter is not insomnia, but a phenomenon of being unwilling to fall asleep because of thinking and memory.
At this point, I'm not sure what kind of situation you are talking about, but it is likely that the current insomnia is related to some kind of anxiety.