“I generally sleep four hours a night, and then I’m up and good to go,” said a woman named Sindi van Zyl, recently profiled by Fast Company as being a “natural short sleeper.” Consisting of less than 3% of the population, natural short sleepers require only four to six hours of sleep per night, and it’s known to be genetic.
“It doesn’t matter what I’ve done the night before, or what I’ve done during the day,” van Zyl continues. “As soon as my four hours is up, I’m awake. At least once or twice a month, I’ll sleep for six hours, and it’s as if my batteries have been recharged.”
Scientists at the University of California San Francisco had already discovered one gene that identifies “short sleepers.” Last week, they discovered a second such gene after a 10-year quest.
Discovering the second gene linked to needing less sleep
“Before we identified the first short-sleep gene, people really weren’t thinking about sleep duration in genetic terms,” said Ying Hui Fu, Ph.D., professor of neurology at UCSF, in a release.
Science was unable to figure out “natural” short sleepers [who didn’t rely on alarm clocks or other artificial aids] until 2009, when Fu’s team did a study and found that people who had inherited a certain gene mutation called DEC2 got, slept, on average, only 6.25 hours nightly. People without the mutation slept about 8.06 hours nightly. This finding was the first conclusive evidence that natural short sleep was – at least, in some cases – genetic. However, since the mutation is rare, it accounted for some natural short sleepers, but not all of them.
“Sleep is complicated,” said UCSF’s Louis Ptáček, MD, the John C. Coleman Distinguished Professor in Neurodegenerative Diseases and co-senior author of the new study. “We didn’t think there was just one gene or one region of the brain telling our bodies to sleep or wake.” Both authors figured there had to be other, undiscovered causes of short sleep.
Researching through three generations of one family
The breakthrough in finding the second short-sleep gene came after the researchers found a family that had three generations of natural short sleepers – but did not have the DEC2 mutation.
To identify the genetic aspect of the family’s short sleep, the researchers used gene sequencing and a technique called linkage analysis, which is used to close in on the exact chromosomal location of mutations associated with a particular trait. They discovered a mutation in a gene called ADRB1 that was associated with natural short sleep.
To understand how this mutation was associated with short sleep, researchers performed experiments on lab-grown cells and on mice that had been genetically engineered to have some kind of mutation, ADRB1.
It’s good to be a short sleeper
In short, the experiments indicated that the mutation of ADRB1 encourages natural short sleep because it helps create brains that are easier to wake up, and that stay awake longer. Also, they won’t suffer from the negative side effects of sleep deprivation.
In fact, there are benefits to being someone who naturally sleeps only four to six hours a night. Short sleepers tend to be unusually optimistic, more energetic, and better multitaskers. They also don’t get jet lag.
As we learn more about short sleepers, they may be helping the rest of us normal sleepers out. Fu said that the work may someday lead to developing new drugs to influence sleep and wake. “Sleep is one of the most important things we do,” she said. “Not getting enough sleep is linked to an increase in the incidence of many conditions, including cancer, autoimmune disorders, cardiovascular disease, and Alzheimer’s.”
Their findings were published in the journal Neuron. The two senior authors were Ying-Hui Fu, a professor of neurology at UCSF, and Louis Ptacek, a neurologist at UCSF. Fu led both research teams that discovered the pair of short sleep genes.