Natural "short sleepers," as they're officially known, are night owls and early birds simultaneously. They typically turn in well after midnight, then get up just a few hours later and barrel through the day without needing to take naps or load up on caffeine.
They are also energetic, outgoing, optimistic and ambitious, according to the few researchers who have studied them. The pattern sometimes starts in childhood and often runs in families.
While it's unclear if all short sleepers are high achievers, they do have more time in the day to do things, and keep finding more interesting things to do than sleep, often doing several things at once.
Nobody knows how many natural short sleepers are out there.Out of every 100 people who believe they only need five or six hours of sleep a night, only about five people really do, Dr. Buysse says. The rest end up chronically sleep deprived, part of the one-third of U.S. adults who get less than the recommended seven hours of sleep per night, according to a report last month by the Centers for Disease Control and Prevention.
Most adults have normal sleep needs, functioning best with 7 to 9 hours of sleep, and about two-thirds of Americans regularly get it. Children fare better with 8 to 12 hours, and elderly people may need only 6 to 7.
Wannabe Short Sleeper
One-third of Americans are sleep-deprived, regularly getting less than 7 hours a night, which puts them at higher risk of diabetes, obesity, high blood pressure and other health problems.
Short sleepers, about 1% to 3% of the population, function well on less than 6 hours of sleep without being tired during the day. They tend to be unusually energetic and outgoing. Geneticists who spotted a gene variation in short sleepers were able to replicate it in mice—which needed less sleep than usual, too.
Dr. Ying-Hui Fu was part of a research team that discovered a gene variation, hDEC2, in a pair of short sleepers in 2009. They were studying extreme early birds when they noticed that two of their subjects, a mother and daughter, got up naturally about 4 a.m. but also went to bed past midnight.
Genetic analyses spotted one gene variation common to them both. The scientists were able to replicate the gene variation in a strain of mice and found that the mice needed less sleep than usual, too.
News of their finding spurred other people to write the team, saying they were natural short sleepers and volunteering to be studied. The researchers are recruiting more candidates and hope to find more gene variations they have in common.
To date, Dr. Jones says he has identified only about 20 true short sleepers, and he says they share some fascinating characteristics."Typically, at the end of a long, structured phone interview, they will admit that they've been texting and surfing the Internet and doing the crossword puzzle at the same time, all on less than six hours of sleep," says Dr. Jones.
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