Don't try to fight it: Your need to sleep is 80 percent genetic

History is filled with stories of highly successful people who barely slept. Thomas Edison and Margaret Thatcher are both said to have gotten by on four hours a night. President Obama reportedly only sleeps six.

But here's the bad news: it's very, very unlikely that you can do the same and still be fully functional in the morning. Scientists estimate that only about 5 percent of people are natural "short sleepers" who feel well-rested after six hours of sleep or less.

only about 5 percent of people are natural "short sleepers"

More recently, researchers have also found that our need for sleep is largely determined by our genes. So if you need eight hours of sleep to feel well-rested, it's impossible to train yourself to get by with less and still operate at peak capacity. (Though that doesn't stop people from trying — surveys have found that about 40 percent of Americans get six hours or less each night.)

One interesting question, though, is whether that could ever change in the future. Lately, sleep researchers have been studying what separates these short sleepers from the rest of us, trying to figure out what it is about their genes that lets them go about with so little slumber. It's possible this research could someday lead to new drugs to help all of us become more efficient sleepers — though it's also possible that messing with our natural sleep needs could have disastrous consequences.

Our need for sleep seems to be about 80 percent genetic

Thanks, family, for my sleep genes. (Shutterstock)

One of the best ways to figure out how much of a given trait is genetic is to look at twins. Identical twins are genetically identical (give or take a few random mutations), whereas fraternal twins are simply siblings that shared a womb — and, like all other biological siblings, 50 percent of their genes. By comparing how these two groups differ for a given trait, researchers can calculate how much of the variance of the trait is from genetic factors.

A group of researchers led by Allan Pack at the University of Pennsylvania did just that for sleep. In a laboratory setting, they deprived 59 pairs of identical twins and 41 pairs of fraternal twins of sleep for 38 hours and tested them with a standard reaction-time test every two hours. The differences in their performance was roughly 80 percent heritable.

Some other studies have looked at twins and surveyed them about how long they usually sleep. Of course, how much sleep people need and how much they actually get can be quite different. But this still shows a genetic trend. These types of analyses generally peg the heritability of actual sleep length at roughly 40 percent to 55 percent.

The search for genes that let people get by with less sleep

I think he found one. (Shutterstock)

This is still a pretty young field. The first sleep genes — which were involved in narcolepsy — weren't found until 1999. But some progress is slowly being made.

In 2009, researchers screening DNA samples from volunteers found two women (a mother and daughter) who could wake up naturally after six hours feeling refreshed. They both had mutations in the same gene, called DEC2 or BHLHE41. The scientists also found that when mice were given this same mutation, they became shorter sleepers that recovered more quickly from sleep deprivation. The group, led by UCSF's Ying-Hui Fu, published their research in Science.

In July 2014, a second paper (also led by Pack and published in the journal SLEEP) linked the DEC2 gene to a need for less shuteye. Maria Konnikova summarized it recently for the New Yorker. Researchers announced that they'd found a different mutation in the DEC2 gene that seemed to account for drastic differences in sleep needs in a pair of 27-year-old brothers. The brother with the unusual mutation usually slept about two hours less. In laboratory tests, he showed less impairment after being sleep deprived and recovered from sleep deprivation faster.

a mutation in the DEC2 gene seemed to account for drastic differences in sleep needs in a pair of brothers

Still, it's unlikely that DEC2 is the only gene that governs our need for sleep. Many other genes have been implicated as well. The Period 3 gene has been found to be associated with attention and cognition after sleep deprivation. And in a study of more than 4,000 people, researchers found that the ABCC9 gene accounts for roughly 5 percent of the variation in self-reported sleep. (That gene codes for a protein that's involved with metabolism.)

So the hunt continues. Another study published in December 2014 in Molecular Psychiatry broadly looked across the genomes of more than 47,000 people and found two general areas that correlated with people's reports of how much they usually sleep. They then replicated those findings in a smaller group of about 4,800 people.

Scientists still aren't quite sure which genes within those areas are the important ones. But they did note that one region is also related to metabolism and the other to psychiatric disorders. At this point, it's difficult to tell if sleep is influencing these other conditions or vice versa (or if underlying genetic factors are causing both).

Could we ever engineer short sleepers?

If only. (Shutterstock)

If researchers end up finding some genes that have a huge influence on our need for sleep, then what? One possibility is that scientists might be able to develop a genetic test to figure out who can likely get by on little sleep — and who can't. Such a test could help people choose lifestyles and careers that better suit their health needs (performing 20-hour surgeries may not be for everyone).

ONE possibility would be to Develop drugs that turn people into more efficient sleepers

Another possibility would be to use this information to develop drugs that turn people into more efficient sleepers. Genes code for various proteins in the body, which means that different genes in short sleepers leads to different amounts of these proteins, too. Theoretically, scientists could find drugs that change the activity of these molecules to help other people sleep less, too. (Though this would likely be decades and decades away.)

In an even more futuristic scenario, scientists might one day be able to permanently alter the relevant genes through gene therapy — engineering humans who can get by with little sleep.

Still, it's unclear if doing so would be wise. Sleep is a complex behavior that's intimately tied to all kinds of other health issues, including metabolism and memory. It's unclear what side effects might come from messing with all of this. Indeed, it's entirely possible that people who can naturally get by with less sleep are paying for it in other ways.

Even if you're not a short sleeper, you can still sleep more efficiently

Do not try this at home. (Shutterstock)

While we wait for science to (maybe) save us, there are more banal techniques that can help the rest of us become more efficient sleepers. We can turn off glowing devices such as phones and TVs an hour before bed (their blue light can mess up your body's production of the hormone melatonin, which makes you sleepy). We can avoid caffeine in the afternoon. And we can keep a consistent sleep schedule — even on the weekends.

If you're not a short sleeper, these tricks won't let you get by with four hours of slumber and feel fine. But they might let you feel a bit better in the morning.

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