They call it “casting off.”
In the first few weeks after arriving in the vertical jungle that is the City, people find the constant assault on their senses, all the light and sound, has the effect of making their schedules more nocturnal. Stores are open 24 hours, transportation runs 24 hours, there is nothing that is not open for business and illuminated, if not always totally safe, at any hour of the day.
Many suffer temporary psychoses from this sudden and often intense change to their sleep-wake cycle, and there are sun lamp parlors and sleep clinics galore to help those with the money to demand it. But one thing, strangely never seems to be at issue for these new Citizens.
They never seem to notice that the shift in their waking life has the effect of cutting them off from all they knew before. “Casting off” is a traumatic separation, a birthing, into a new milieu. The City accepts all who seek it, but only if they are willing to pay its price.