[mathteacher1729]

There are plenty of variables that influence "productivity" (however that is defined) but I imagine that the amount of sleep required for maximum productivity varies from person to person.

In my personal experience I've known people who require 3 to 4 hrs/night, and others (myself included) who need between 8 and 9. During times when I'm feeling my absolute best, physically and mentally, I get about 2 hours of rigorous exercise, 8 to 10 hours of productive work, and roughly 8 hours of sleep a day with the rest of the time filled in by preparing and eating food, taking short breaks, hobbies, relaxing, etc.

Wild hypothesis: Most people would agree that the amount of sleep they require to "feel and do their best" (assuming ideal exercise, diet, etc.) falls within a normal distribution with mean 7 hours and standard deviation of +/- 3 hours.

--- edit: spelling

[ezy]

"8 to 10 hours of reproductive work"

Yes, this would tire me out as well. :-)

Seriously, I've found that my normal schedule appears to be 7 hours solid, with a 1.5 hr nap, depending. Without an alarm, I wake up 7 hrs later on the dot (and can't get back to sleep), but then require a nap 8 hrs later to make it through the day. I cannot sustain 6 hrs and a 2-3 hr nap for any length of time (maybe a couple of days before I feel like crap).

I wonder how many different variations of these kinds of cycles there are among the population and how they vary from the 1st to the 3rd world.

[mathteacher1729]

Hah, thank you for pointing out the spelling error. :)

As for the variations in the sleep cycles, I think it would have to do with the length of time between REM cycles in individuals. I'm sure there's individual variance in both the length of the cycles and how many cycles are needed for "A good night's sleep".