A new drug called Modafinil appears to let people get by with much less sleep which could have a large impact on society and the economy. Garrett Jones offers some speculations about this, but I think the main thing that needs to be emphasized is simply that it's very hard to say what the real implications are.
The most important place to start is probably just to remember that the world is a great big place full of enormous diversity. People in certain kinds of high-status professions—CEOs and Ezra Klein and such—will presumably be de facto required to work 18 hour days if they can get by on two hours of sleep. All the way at the other end of the spectrum, people like migrant factory workers in China (or whatever the new China is in terms of sweatshop work) will probably do the same, working super-long workweeks in order to save up money and go back home.
But beyond that ... I dunno. A larger labor supply could push down wages reversing the historic trend toward shorter working hours in developed countries. But that's a bit simplistic. Wages aren't lower in Boston than in Bangor because of the larger labor supply. Maybe less sleep-deprived workers would be more productive and wages would go up. Maybe consumption of local services would skyrocket (more nights out on the town) and demand for labor would rise. Maybe all those doped-up CEOs working 18 hour days would start spectacularly mismanaging their companies, yet nobody would be willing or able to admit that it would make more sense to put in fewer hours.