There is a mod that can manage the days/weeks, but I don't think that's what you want. Citizens have (in theory) a 24 hour day, split 8/8/8 between working, free time (at home resting) and meeting their needs (shopping, cinema, sport etc.). It's a little more complicated than that because they can also have a few hours travelling to work to include, so their cycle doesn't quite match the 24 hour daily cycle.

So they do have sleep/rest times. But they do not all have sleep times at night, there is as much activity at night as in the day. This cannot be controlled - all workplaces operate 24x7 and 365 days per year. This makes sense with some heavy industrial workplaces, but not with shops, pubs, but these need to stay open to allow the workers who have been at work during the day to go to buy meat, then still go and play sports...

The workers are randomised in the start of their working/free time/needs cycle, so there are always some starting work throughout the 24 hours. That means they are also randomised going shopping etc. Shopping or playing sports can take place as much at 3:00 in the morning as 18:00 in the evening. This cannot be controlled.

In a script mod you can set the age of a worker, their status (happiness, loyalty etc.) and their education level. But you cannot change their daily routine, when it starts, what they do, where they go and how much time they spend on each activity. This is all handled by core code in the game, and as far as I can see currently cannot be scripted/modded.

Thanks so much Potsky for the information. I would say that it would already be a step forward towards "control" of the days.

Could you tell me the MOD?