Do Some People Need Less Sleep?

In a new study conducted at the University of California San Francisco (UCSF), a team of researchers has discovered a genetic link that could explain why some people need a full eight hours of sleep while others can get by on just five or six.

Over the last decade the genetics associated with circadian rhythms has been well studied, though few scientists have explored the role that other genes play in sleep patterns. By studying members of a family who function on significantly less sleep than average, the UCSF researchers were able to pinpoint a new gene that they believe affects how much sleep the body needs.

"It's remarkable that we know so little about sleep, given that the average person spends a third of their lives doing it," says Louis Ptáček, a neurologist at UCSF and one co senior author of the study. "This research is an exciting new frontier that allows us to dissect the complexity of circuits in the brain and the different types of neurons that contribute to sleep and wakefulness."

Pinpointing the role of ADRB1

The findings were reported in the journal Neuron and explain how the team analysed the sleep patterns and genetic frameworks of several member of a family who get just six hours of shut eye a night. Using advanced whole-exome sequencing and genetic linkage techniques, the team identified a rare variant called ADRB1.

The first step in pinpointing the role of ADRB1 was to study its protein. The team them conducted experiments on mice carrying a mutated version of the ADRB1 gene. They found that on average, mice with the rare variant needed 55 minutes less sleep than their counterparts.

"We wanted to determine if these mutations caused any functional alterations compared with the wild type," explains Ying-Hui Fu, a UCSF geneticist and co senior author of the study. "We found that this gene codes for ß1-adrenergic receptor, and that the mutant version of the protein is much less stable, altering the receptor's function. This suggested it was likely to have functional consequences in the brain."

An important step in sleep science

Further analysis showed that ADRB1 is present at high levels in the dorsal pons, a region of the brainstem associated with subconscious activities such as sleep, eye movement and respiration.

While Fu admits that mice adhere to different sleep patterns than humans, he says the discovery of ADRB1 is an important step in sleep science. She predicts that eventually, studies such as this could be used to develop new types of drugs to control sleep patterns and treat insomnia.

"Sleep is one of the most important things we do," says Fu. "Not getting enough sleep is linked to an increase in the incidence of many conditions, including cancer, autoimmune disorders, cardiovascular disease, and Alzheimer's."

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