Who are these people that only work 3.8 hr per day and get 8.8 hr of sleep. I am lucky to get more than 5.5 hr of sleep and I work far more than 3.8 hr per day. Sounds like the average joe has it made. Oh where did I go wrong :-P
This is pretty clearly a case of the mean conveying little useful information. Children, elderly, and the unemployed skew the data way too much for the average to be a meaningful summary.
I suspect that's an average of people who work full-time, people who work part-time, and people who don't work at all, such as unemployed, retirees, and children.
One of the big factors is actually weekends. 40hrs/7days = 5.7hrs/day.