According to this article, people tend to report better moods, greater vitality, and less pain/complaints on the weekends. This improvement in functioning results from increased choice in the activities one engages in, as well as the ability to spend more time with family and friends. From the article:
"Workers, even those with interesting, high status jobs, really are happier on the weekend," says author Richard Ryan, a professor of psychology at the University of Rochester. "Our findings highlight just how important free time is to an individual's well-being," Ryan adds. "Far from frivolous, the relatively unfettered time on weekends provides critical opportunities for bonding with others, exploring interests and relaxing -- basic psychological needs that people should be careful not to crowd out with overwork," Ryan cautions.
Of course, I have been running a long-term single-case experimental design that is consistent with these findings. I also believe a certain restaurant chain has marketed itself to these week-end benefits to great financial success.
In all seriousness, the preference for self-determination is an important consideration when it comes to a person's sense of well-being, and the article notes that workplaces should continue to explore ways of increasing the sense of autonomy and choice in their employess. From the article:
The results support self-determination theory, which holds that well-being depends in large part on meeting one's basic psychological needs for autonomy, competence, and relatedness. This study, conclude the authors, "offers one of the first substantive and theory-based explanations for why wellbeing tends to be more favorable on the weekends: People experience greater autonomy and relatedness, which are, in turn, related to higher wellness." By contrast, write the authors, the work week "is replete with activities involving external controls, time pressures, and demands on behavior related to work, child care and other constraints." Workers also may spend time among colleagues with whom they share limited emotional connections.
Then again, hasn't this already been covered in various media? For example: