There's another, more sci-fi way we may be able to sleep less. Lots of people claim to be "short-sleepers" who function perfectly well on six or even four hours of shut-eye. CEOs and politicians (see Bill Clinton) love to brag about how little rest they need. In fact, says Penn's David Dinges, almost nobody is a true short-sleeper. Some who purport to need only four hours sack time cheat by napping frequently. Others are very sleep-deprived and just don't realize it. Dinges has measured actual performance of self-described short-sleepers, and their lousy performances prove that they're wiped.

But a rare few—1 in a 1,000, Dinges estimates—need very little sleep and function just as well after six hours as after eight. This group is very hard to study (since it takes enormous effort just to weed out the many ersatz short-sleepers from the real ones).

Short-sleeping probably has genetic roots. Scientists are now starting to hunt the human genome for the genes connected to sleep regulation. If they find a short-sleeping gene, it would be a glorious target for gene enhancement. For now, no one has found such a gene or even knows if it exists. If it is found, scientists will need to determine if its presence exacts other physiological costs. (If you sleep less, do you die sooner, for example?) And even if there aren't any costs, researchers face the technical challenge of modifying DNA in a remote area of the brain—a task well beyond current gene therapy, which tends to focus on small genes in accessible corners of the body.