As several people said it differs from country to country and from mental house to mental house.
I can speak of my country - one in
and for several houses I was in.
It is boring as hell - in every place I was in, boredom was the most difficult issue.
You are thrown out of the bed in the morning (usually in every mental house)
Your room is locked for whole day between 8:00 and 18:00.
Nobody takes care of you, except few hours in the morning.
Food is very bad.
Your only activity can be sitting and watching TV (very censored), reading a book, playing some very childish board game or walking in the corridors back and forth (which most people do).
You are forced to take medicine.
You pray for your release every day.
You are allowed to smoke in the dedicated place.
EDIT: I forgot to wrote that every mental house is usually divided into several departments. These departments vary from the perspectivity (How long they think you will need to be there) and also vary how they think can trust you (closed/semi-closed/open departments).
My experience is usually for the semi-closed depts. I was never in closed one. From what I hear and saw, it looks like prison there. When I get to open departments (Usually in the end of my treatment),there were at least signs of some therapy, usually in the morning and you were also allowed to go outside for several hours, sometimes even alone to go to a shop and buy something.
The biggest bullshit of our system is however that people with any diagnosis can be in one deparment. I was in one department with drugg addicted, people after unsuccessful CTB, depressions, anxiety disorders, bulimia, psychotics, schyzofrenia, bipolar disorder... People with every diagnosis together in one place...