Answer:
The days you go to college you have an established routine. You must wake up at a certain time and have schedules for each class. You should also sleep early to repeat this routine the next day.
The days you go out with your friends however you can be more unstructured. If it is a weekend and you should not go to university or study for any exam, you can sleep late and not worry about the schedules and responsibilities that you face a week day.