The Magic Powers of Sleep

I sleep plenty. 7-9 hours per night (I used to sleep more when I was younger, except for a disastrous 1.5 years plagued by Mormon seminary).

“Sleep spindles predict learning refreshment,” said Matthew Walker, associate professor of psychology and neuroscience at UC Berkeley. “A lot of that spindle-rich sleep is occurring the second half of the night, so if you sleep six hours or less, you are shortchanging yourself. You will have fewer spindles, and you might not be able to learn as much,” said Bryce Mander, a post-doctoral fellow in psychology at UC Berkeley and lead author of the study.

Maybe. Or if you sleep less, maybe the sleep spindles become more densely packed per hour of shut-eye, just like REM sleep. I do agree that you should expect to lose out in a big way on 6 hours/night of sleep, though (even for one night).