When you're in jail sometimes you might be able to sleep all day and just lay around all day depending on the jail.
Other jails may actually make you stay awake after waking you up at a certain time in the morning for breakfast and then they may have a required work program where you will be required to do some work inside the jail such as cleaning, sweeping etc.
Jail is not meant to be a fun place and doesn't mean that you will just get to sleep all day at least in most jails.
I used to work at a jail as a guard and the inmates were not allowed to sleep because we wanted the inmates to suffer their punishment.
You had to be awake during the day in the jail unless you had some medical condition that made you sleep more often.
But other than that you had to be up at 5:00 AM and had to stay awake until bedtime and then had to wake up again at 5:00 AM to get counted again.