"Here there was no real morning or evening, day or dark; the dwellers seemed to live according to whim." (Chapter Eight, p. 48)
What would that do to metabolisms? And what would agelessness do to psychologies? Will such conditions exist in the future?
The immortals in Anderson's World Without Stars:
edit their memories;
thus, only ever consciously remember a few decades;
but know that they have lived for centuries or millennia;
The immortals in his The Boat Of A Million Years learn how to prevent memory overload by developing mental techniques without any help from technological editing.
His Time Patrolmen:
can spend years or decades in past centuries but return to the moment when they left their home era;
remember some experiences that did not occur in their current timeline;
live and work for decades with a home base in, e.g., late twentieth century New York, but then, instead of retiring, move to a new home base in, e.g., earlier twentieth century Paris;
apparently do not retire.
What does that do to their experience and perception of time?