Working a 4 day week doesn't necessarily mean working less that 40 hours. I worked 4-10 hr days for awhile and loved it. Companies have found that productivity actually increases with 4-10's, workers have only 4 days to mill around in the morning getting coffee and gossiping. Additionally, your commuting costs are reduced 20%, and things like going to the doctor, dentist, drivers license, etc can be taken care of without taking off from work. Income remains the same, commuting costs are reduced 20%, it's like getting a raise, and you can get stuff done during the week providing more free time on the weekend.