Dan Aspey claims he can do well on 5 hours of sleep, and then makes a further claim that any other adult (he recommends not trying to do serious sleep reduction until you're past 23) can also do well on 5 hours. To judge by a fast look at the comments, rather few of his readers are trying this, let alone succeeding at it.
Do you have any information about whether Aspey's results generalize?
Not really.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.