Incarceration can have a pretty bad affect on a persons mental health and can cause severe depression especially if the inmate is incarcerated for longer periods of time as in longer than a year.
I would imagine that if you were to be incarcerated for longer than a year then the time that would seem to fly by when you're were at home would seem to slow down to a crawl and then months would seem like years and days would seem like months.
Some prisoners have said that they eventually get used to being in prison and that they do what they can to take their mind off the time and time seems to go at the same speed as it did when on the outside or it seems to speed up.
Some prisoners can have jobs in the prison that help their time go by faster instead of just sitting idle and doing nothing which makes time seem to drag.
Prison can be pretty boring so you have to do what you can to take your mind off the time and I've heard that as your time gets close to be released that time starts to slow down again as you're waiting on that clock to move and it seems to go slow while your paperwork is getting processed.
But when you're out of prison again the time starts to speed up again.
Still time is always going at the same pace but it can seem to drag on while in prison or you can make it seem to go fast if you take your mind off the time and take on a job in the prison to keep you occupied.