an alternative to the solar-day-based sleep schedule. approx 19 hours waking, followed by 9 hours of sleep. a "week" is six of these 28 hour days. 6 days of 28 hours each matches exactly with a "normal" week of 7 24 hour cycles, so on a given day of the calendar week, you always have the same bed and wakeup times.

bedtime is 4 hours later every calendar day, sleep times rotate around the face of the 24 hour clock.

this schedule lets you take advantage of quiet and often more productive hours late at night, yet still interact with a largely diurnal outside world several days a week. it also gives you longer blocks of productive time for work or play or partying, while still getting plenty of sleep.