Rare genetic mutation shortens sleep cycle to six hours

By Allie Curwin Staff Writer


On a typical Monday morning, adults and children alike struggle to drag themselves out of bed and get on with their day. However, for the few people with the hDEC2 sleep mutation gene, functioning on a minimal amount of sleep is not a problem, it’s a lifestyle.


According to Ying-Hui Fu, Professor of Neurology at University of California San Francisco, these “short sleepers” have a genetic mutation in their gene hDEC2, which regulates their sleep-wake cycle. The mutation was first discovered in a study in 2002. The gene allows them to function normally on less sleep than the average person, often feeling well rested after a short night’s sleep.


“The hDEC2 sleep mutation was discovered as part of a study investigating genes that control circadian rhythm in adults,” said Dr. Jimmy Holder, who works at the Department of Pediatrics at the Baylor College of Medicine and helped with the study. “There are individuals who are natural ‘morning larks’ due to mutations in genes that control circadian rhythms, the 24-hour biological sleep cycle.”


 People with this mutation have two to three more hours to do things each day than an average person.  They wake up early and have no problem staying energized all day long.


 The mutation was discovered after a family was suspected of having multiple members with the same mutation in the hDEC2 gene. So far, 20 to 30 people have been proven through lab experiments to have this specific sleep mutation.


“No population-based studies have been conducted, but I suspect it is quite rare,” Holder said. 


The average amount of sleep each night for those with the mutation is about six hours. They usually go to bed at a normal time, but automatically wake up around four or five in the morning.


Some doctors, however, suspect that the gene could result in negative health effects in the future. Although the lack of sleep is natural for those with the hDEC2 gene, many functions of the body rely on getting around eight hours of sleep each night.


According to a March 12 CNN.com article, those who force their bodies to function on less than seven to eight hours are likely to face health issues. Sleep deprivation often results in drowsiness, driver’s fatigue and poor hand-eye coordination. Lack of sleep significantly decreases performance, cognition and attention levels.


“Sleep seems to help with consolidating memories and concentration,” Holder said.


Those with the mutation are able to make a habit of sleeping for four to six hours each night and still function well, but those without the hDEC2 mutation are unable to train themselves to need less sleep.


“Sleep is under homeostatic control,” Holder said. “This means although you can force yourself to stay awake for longer periods of time than usual, you will need to repay your sleep debt in the future and sleep more later.”


The hDEC2 genetic mutation is not the only sleep gene mutation. Scientists have discovered a variety of other mutations that affect the sleep wake cycle and cause people to sleep less. Sleep doctors and scientists continue to experiment and expect to find many other mutations in the near future.


“There will be many more mutations to come and we already know many people who have similar phenotype but do not have this particular mutation,” Fu said.