A University of Rochester study finds that most people feel better, are happier, more energetic, and have less perceived pain on the weekends.

I guess the professor is suffering an imagination deficit, and couldn't think of any less obvious, less well-known psychological phenomenon to study. It comes under the category of "Duh, dude".

The reasons people felt mentally and physically better? I'm sure you can come up with the list on your own. People have deeper connections with family and community than they do with coworkers; weekends allow them time to enjoy those relationships.

People have more autonomy on the weekends than they do during their working hours, even managers supposedly in charge of things.

People choose their own activities on the weekend (to some extent) and the tasks they undertake are usually familiar and/or enjoyable, enhancing their feelings of competence.

Under less stress, people can relax and experience less time pressure, bond with others, explore interests, and relax--all basic psychological needs.

Moral of the story: don't bring work home.