Mutation Tied to Need for Less Sleep Is Discovered
Researchers have found a genetic mutation in two people who need far
less sleep than average, a discovery that might open the door to understanding
human sleep patterns and lead to treatments for insomnia and other sleep
disorders.
The finding, published in the
Friday issue of the journal Science, marks the first time scientists have
identified a genetic mutation that relates to sleep duration in any animal or
human.
Although the mutation has been identified in only two people, the power
of the research stems from the fact that the shortened sleep effect was
replicated in mouse and fruit-fly studies. As a result, the research now gives
scientists a clearer sense of where to look for genetic traits linked to sleep
patterns.
“I think it’s really a landmark study,” said Dr. Charles A. Czeisler, a
leading sleep researcher and chief of sleep medicine at Brigham and Women’s Hospital in
The gene mutation was found by scientists at the University of California, San Francisco, who were conducting DNA screening on several hundred
blood samples from people who had taken part in sleep studies.
The scientists were searching the samples for variations in several
genes thought to be related to the sleep cycle. In what amounts to finding a
needle in a haystack, they spotted two DNA samples with abnormal copies of a
gene called DEC2, which is known to affect circadian rhythms. They then worked
back to find out who provided the samples and found a mother and daughter who
were naturally short sleepers. The women routinely function on about 6 hours of
sleep a night; the average person needs 8 to 8.5 hours of sleep.
When scientists bred mice with the same mutation, the animals slept less
and recovered quicker from periods of sleep deprivation compared with regular
mice.
“We know sleep is necessary for life, but we know so little about
sleep,” says Ying-Hui Fu, study co-author and professor of neurology at the
What distinguishes the two women in the study and other naturally short
sleepers is that they go to bed at a normal time and wake up early without an
alarm. The two women, one in her 70s and the other in her 40s, go to bed around
10 or 10:30 at night and wake up alert and energized around 4 or 4:30 in the
morning, Dr. Fu said.
“When they wake up in morning, they feel they have slept enough,” Dr. Fu
said. “They want to get up and do things. They arrange all their major tasks in
their morning.”
Dr. Fu said that while many people might sleep only six or fewer hours a
night, most were not naturally short sleepers. For instance, they use
stimulants and alarm clocks to maintain a shortened sleep schedule.
“Many people get only six hours of sleep a night, but we drink coffee
and tea to make ourselves stay up,” she said. “That’s a very different thing.
Our body needs 8 to 8.5 hours.”
The genetic mutation appears to be rare. Out of 70 families with known
sleep problems studied at the university, only one family carried the mutation.
Dr. Fu said fewer than 5 percent of people appeared to be naturally short
sleepers.
The real benefit of the research will come if and when the mutation is
identified in other individuals. That could lead to new discoveries about sleep
timing and duration, and possibly new treatments for sleep disorders.
Dr. Fu said her “fantasy” was that the finding might eventually lead to
a safe treatment for people who wanted or needed more awake hours and were
looking for a way to get by on less sleep without harming their health.
Source: nytimes.com