Staying wakeful for the day: A second short sleep gene identified

How come? Only about 10 years ago sleep researchers discovered that people who had inherited a particular mutation (i.e., hDEC2-P385R) in a transcriptional repressor gene called DEC2 averaged only 6.25 hours of sleep per night, while study participants lacking the mutation averaged 8.06 hours. At the time, this finding provided the first evidence that natural short sleep has, at least in some cases, a genetic basis. But this mutation is rather rare in the general population, so while it helped explain some natural short sleepers, it couldn’t possibly account for all of them. Moreover, experts in sleep research were thinking all along that there had to be other, as yet undiscovered genetic causes of short sleep.

In fact, after a 10-year long search, scientists have now identified a second ‘short sleep’ gene. A new study just published in the Journal Neuron as of August 28, 2919 describes a breakthrough in sleep research when the researchers identified a family that included three successive generations of natural short sleepers, none of whom harbored the DEC2 mutation identified earlier as the first ‘short sleep gene’. The researchers used gene sequencing and a technique known as linkage analysis, which helps scientists pinpoint the exact chromosomal location of mutations associated with a particular trait, to comb through the family’s genome. Their efforts uncovered a single-letter mutation in the β₁-adrenergic receptor gene ADRB1 that, like the mutation in the DEC2, was associated with natural short 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 and a member of the UCSF Weill Institute for Neurosciences. Dr. Fu led the research teams that discovered the first and now the second short sleep genes. According to Dr. Fu, many scientists once thought that certain sleep behaviors couldn’t be studied genetically. “Sleep can be difficult to study using the tools of human genetics because people use alarms, coffee and pills to alter their natural sleep cycles,” she said. These sleep disruptors, the thinking went, made it difficult for researchers to distinguish between people who naturally sleep for less than six hours and those who do so only with the aid of an artificial stimulant. One of the breakthroughs came now  when the researchers identified a family that included three successive generations of natural short sleepers, none of whom harbored the DEC2 mutation.