Four-day week Four-day week A four-day week is an arrangement where a workplace or school has its employees or students work or attend school over the course of four days rather than the more customary five. This arrangement can be a part of flexible working hours, and is sometimes used to cut costs, as seen in the example of the so-called "4/10 work week," where employees work a normal 40 hours across four days, i.e. a "four-ten" week. In 2008, employees of the Utah state government all began working ten-hour days from Monday to Thursday. By closing state government offices on Fridays,
Eight-day week popularity of the seven-day rhythm won and the eight-day week disappeared. The cycle of seven days, named after the sun, the moon, and the five planets visible to the naked eye, was already customary in the time of Justin Martyr, who wrote of the Christians meeting on the Day of the Sun (Sunday). Emperor Constantine eventually established the seven-day week in the Roman calendar in AD 321. The Celts used periods of darkness such as night and winter to begin their calculations of time. This meant that the first period of time in a "week" was a night, followed by