Six Hours Sleep Is Plenty for Lucky Few With Rare Gene Mutation
By Rob Waters
Aug. 13 (Bloomberg) -- An uncommon gene variant seen in a mother and daughter may help explain why some people are perky after six hours of sleep while others are fatigued and function poorly if they get fewer than eight hours regularly of shut-eye.
Sleep researchers at the University of California, San Francisco, found the woman and her daughter wake up refreshed by 5 a.m. after going to bed at 11 p.m. the night before, said
Ying-hui Fu, a professor of neurology. The two were the only people of about 1,000 studied to show the unusual gene variant, Fu said.
Sleep disorders and deprivation affect 50 to 70 million Americans, account for about $15 billion in medical expenses and cost industry $50 billion in lost productivity,
according to the National Institutes of Health. The findings, published today in the journal
Nature, could help scientists understand the complex brain mechanisms that govern the need for sleep, Fu said in a telephone interview.
“We know sleep is important for life,” Fu said. “We know that people who don’t sleep enough have a lot of health problems. Maybe we can find a drug that regulates the brain’s pathways in a similar way so people can sleep for six hours and be healthy and feel fine.”
‘Early to Bed’
Fu and her colleagues had previously identified some of the genes that regulate the body’s
circadian rhythms, including one that causes people to take
Benjamin Franklin’s “early to bed, early to rise” advice to extremes.
“People with that mutation -- they really have to go to bed early,” Fu said. “If they stay up until 10 p.m., it’s like you feel if you stay up until 2 a.m. or 3 a.m.”
Publicity from those findings led patients and doctors to contact Fu and her colleagues and they began collecting and scanning DNA samples from people with unusual sleep patterns, she said. As they reviewed the gene sequences in their collection, they noticed the mother-daughter pair that shared a mutation of a gene called
DEC2 and learned about their reduced need for sleep.
To test whether the DEC2 variant was truly responsible, they engineered mice and later fruit flies to carry the same mutation. The mutant rodents also needed less sleep and recovered more quickly from bouts of sleep deprivation induced by bright lights and frequent pokes and nudges, Fu said. The mice were hooked up to brain-scanning instruments and exhibited brain-wave patterns that suggested they had gotten plenty of sleep, even though they’d had less than usual, she said.
Sleep Needs
The finding suggests there is a range of sleep needs among people based on their individual genetic patterns, Fu said.
“There are people who sleep six hours naturally because that’s what their body needs,” Fu said. “On the other hand, there are many people who sleep six hours but their bodies really need more than that. These are very different things. The mutation we identified can provide an explanation for why our subjects are fine with lifelong short sleep.”
Fu said it is likely that variants of other genes may also cause the same effect and she and other researchers will be searching for them.
The study provides new insights into the genetics of sleep and may help doctors develop treatments, said Donna Arand, a researcher at the
Sleep Disorders Center at Kettering Hospital in Dayton, Ohio.
“Total sleep time is not the primary factor that restores the body but some process that occurs during sleep,” Arand said yesterday in a telephone interview. “Identifying these underlying processes will help clinicians understand the function of sleep and get a clearer understanding of the underlying cause of some sleep disorders.”
The research may show that insomnia and other sleep disorders “aren’t just psychological or behavioral problems or related to depression, there’s a physiological mechanism at work that can account for this behavior,” she said.
The study was funded in part by the
National Institutes of Health.
To contact the reporter on this story:
Rob Waters in San Francisco at
rwaters5@bloomberg.net.
Genetic Mutation and Sleep
Reply With Quote
