sleep cycle reduction

[Jhanananda]

It has been reported by our case histories that it is typical of those who meditate deeply on a regular basis require less sleep.  The following article in Scientific American shows that Hunter–Gatherers typical average about 6.5 hours of sleep.

Modern Hunter–Gatherers Probably Get Less Sleep Than You Do

The researchers looked at people living in three hunter-gatherer societies in rural parts of Africa and South America. Investigations showed that these traditional peoples slept slightly less than 6.5 hours a night on average. In comparison, people in industrial societies usually average seven to eight hours per night.

"We find that contrary to much conventional wisdom, it is very likely that we do not sleep less than our distant ancestors," said the study's senior author, Jerome Siegel, a sleep researcher at the University of California, Los Angeles.

However, the researchers also found that insomnia may have been more rare in ancient times than it is now...

[jay.validus]

How interesting.  I find when I sleep less I tend to have more energy overall, but with more sleep I feel more rested.