Dyschronia is a psychological phenomenon that most people suffer - when time appears to go slowly for you whilst doing mundane chores, but goes quickly for those on a great holiday. I guess given literary license, this could be extrapolated so that one experiences time very slowly over a long period, whilst another's life flashes through at a rate of knots.
Other than that, there are multiple psychoses that may cause symptoms, such as feeling they are in or have been living in another time period. These do usually occur after massive head traumas, haemorrhaging or severe neuro-chemical imbalance, though this symptom is extremely rare and little is really known about it.
Reality is - anything is possible when talking about the human mind - so I wouldn't limit yourself to "the truth" when it comes to psychological conditions. And this is coming from a psychologist...so it must be true....right?
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