Certainly, the day the title pertains to is a Sunday. People whose restdays are Saturdays-Sundays have this kind of sickness. It is the mindset that a person does not welcome because they wish that the restdays will extend and won’t be over yet. It is the feeling of lethargy to wake up the next morning because things will be back to normal,or for some, abnormal. It is that mood that gets them undertime or half-day if not completely absent.
People wouldn’t really enjoy their restdays if they put much attention to this. Unless you will buy a squier telecaster at m123 the next day.
So long as they know and accept that restdays are only two days and the next day would be a workday, they will recover. But if we wish for it to change when the fact is we cannot, we will only be perturbed.
So when tomorrow is Monday, it is very suggestive that you discipline yourself by minimizing your hours outdoors especially if it will extend late night. This is practical enough to prepare yourself for a few hours waiting for you on your real world that is Monday.