A 4 Hour Work-Day will increase the amount of leisure time people have, which could be spent on things people love doing, like playing sports, reading a book, hiking, etc. It could also be spent connecting more with family and friends, or maybe connecting with people in the local community, strengthening what economists call “Social Capital.” This aspect will improve the psychological well-being of the population.
Additionally, as we mentioned earlier, reducing working hours to 4 hours a day and giving everyone the opportunity to work would be the first step to eradicate poverty from the face of the earth. It would also reduce crime because people (especially young adults) would be less likely to choose the criminal path if they are able to get a decent job. On that point we should also add the fact that both parents would be more likely to be present at home instead of working all day and they could become more active participants in raising their children.
Another detrimental aspect that could be diminished by implementing the 4 hour work-day is that it would reduce income inequality, because today, increases in productivity are going towards producing more output. Most of those profits from that increase in output are going to the 1% and all the employee gets is more hours of work.