Gene Cuts Need for Sleep
People With Rare Gene Mutation Refreshed by 6-Hour Sleep
Aug. 13, 2009 - At age 69 she's never slept more than six hours a day -- no
naps -- yet she's healthy and far more active than most people.
Her 44-year-old daughter also goes to bed at 10 p.m. and gets up at about 4
a.m., even when on vacation. The two share a rare mutation in a gene called
DEC2. People with this mutation, researchers find, need less sleep.
The gene is the first ever linked to human sleep behavior. The discovery
comes from Ying-Hui Fu, PhD, of the University of California, San Francisco,
"The most interesting thing for me is this genetic mutation can lead to a
human behavior trait," Fu tells WebMD. "We cannot blame everything on genetics,
but it is obvious our genetic composition affects our behavior. What is
involved in regulating our sleep need? This opens the door to start looking at
It's a key finding that other researchers have long been trying to find,
says Mehdi Tafti, PhD, a geneticist and sleep researcher at the University of
Lausanne, Switzerland. Tafti was not involved in the Fu study.
"This is the first time a gene has been found in humans that critically and
dramatically controls sleep," Tafti tells WebMD. "We now have evidence that a
gene mutation can dramatically change the amount of sleep you get."
Many people set their alarms to go off only six hours after they go to bed.
But nearly all of them get some kind of "power nap" during the day to keep them
going, says sleep expert Richard Simon Jr., MD, medical director of the Kathryn
Severyns Dement Sleep Disorders Center in Walla Walla, Wash.
"Most people who get only six hours' sleep a night finally crash," Simon
tells WebMD. "People who really need six hours' sleep and no more are in the
minority. Most who get only six hours are going through life exhausted."
Short-Sleep Gene: First of Many to Come?
Although the discovery of the effects of the DEC2 mutation is a major
finding, Tafti is quick to note that it affects only one part of the complex
"DEC2 is probably a very, very rare mutation. It was found in one family out
of 60," he says. "So this mutation explains only some 1% of short sleepers, and
we are far from having a complete story."
To prove that the gene affects the need for sleep, Fu and colleagues
genetically engineered mice to carry the human DEC2 gene. Sure enough, the mice
slept less and stayed awake longer.
When the mice were deprived of sleep, the mutant mice needed less sleep to
recover when they finally were allowed to rest.
"These mice just don't need as much sleep," Fu says.
Why? Fu thinks the mutant gene somehow helps mice -- and people -- overcome
their sleep need while somehow allowing them to sleep just long enough to stay