Why some sleep more, some less

Print edition : January 19, 2018

Scientists have identified differences in a group of genes that might help explain why some people need a lot more sleep —and others less—than most. The study, conducted using fruit fly populations bred to model natural variations in human sleep patterns, provides new clues about how genes responsible for sleep duration are linked to a wide variety of biological processes.

Researchers said a better understanding of these processes could lead to new ways to treat sleep disorders such as insomnia and narcolepsy. The study, led by scientists at the National Heart, Lung, and Blood Institute (NHLBI), in the United States, was published in the journal PLOS Genetics on December 14.

“This study is an important step toward solving one of the biggest mysteries in biology: the need to sleep,” said study leader Susan Harbison, an investigator in the Laboratory of Systems Genetics at NHLBI. The scientists said that the involvement of highly diverse biological processes in sleep duration might help explain why the purpose of sleep has been so elusive.

Scientists have known for some time that, in addition to our biological clocks, genes play a key role in sleep. and that sleep patterns can vary widely. But the particular genes controlling the duration of sleep and the biological processes that are linked to these genes have remained unclear.

The scientists artificially bred 13 generations of wild fruit flies to produce flies that were either long sleepers (18 hours each day) or short sleepers (three hours each day). They then compared genetic data between the long and short sleepers and identified 126 differences among 80 genes that appear to be associated with sleep duration. They found that these genetic differences were tied to several important developmental and cell-signalling pathways. Some of the genes identified have known functions in brain development and roles in learning and memory, the researchers said.

“What is particularly interesting about this study is that we created long- and short-sleeping flies using the genetic material present in nature, as opposed to the engineered mutations or transgenic flies that many researchers in this field are using,” Susan Harbison said. “Until now, whether sleep at such extreme long or short duration could exist in natural populations was unknown.”

Compiled by T.V. Jayan