Some experts believe that sleep reduction gadgets will intensify the planet's income inequality problem, because only wealthy people will be able to afford them and can spend those extra waking hours working, making the rich even richer.

In the next 20 years, military leaders will unlock the secret to needing only two hours of sleep a night, using a "combination of devices and chemicals," predicted Marcelo Rinesi of the Institute for Ethics and Emerging Technologies. Rinesi predicts that once scientists work out the glitches and reduce negative side effects, the productivity-boosting machines will become available to civilians.

Like computers, early models of these sleep innovations will likely cost tens of thousands of dollars, offering a biological advantage to those who are already economically advantaged, Rinesi said. That will likely trigger outrage and protest, he predicted. "The social and economic impact is going to be huge. It's going to create a lot of resentment and envy. We are not used to wealthy people having a completely different biological experience of being alive."