If you’re the sort of person who enjoys a little nap in the afternoon, you might not be able to help it – because it could be in your DNA.
Researchers from Massachusetts General Hospital (MGH) have found several gene regions that appear to be related to the tendency to take naps during the day,
They used data from the UK Biobank, which includes genetic information from 452,633 people for the study, published in Nature.
The researchers say some people who wake up early may "catch up" with a nap, while others need a nap because of disturbed sleep – and others may simply need more sleep.
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Hassan Saeed Dashti of Harvard Medical School said napping is "somewhat controversial", and that it’s difficult to disentangle napping from the culture around it, such as in Spain where it used to be part of the culture but is now discouraged.
"It was important to try to disentangle the biological pathways that contribute to why we nap,” he wrote.
Participants wore fitness-band-style acceleratometers to monitor their activity and filled in quizzes on whether they napped "rarely", "sometimes", or "usually".
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The researchers performed a genome-wide association study (GWAS), which involves rapid scanning of complete sets of DNA, or genomes, of a large number of people.
A large number of the genes near or at regions identified by the GWAS are already known to play a role in sleep, such as KSR2, which has previously been found to play a part in sleep regulation.
Several gene variants linked to napping were already associated with a neuropeptide called orexin, which plays a role in wakefulness.
Iyas Daghlas, a medical student at Harvard Medical School, said: "This pathway is known to be involved in rare sleep disorders like narcolepsy, but our findings show that smaller perturbations in the pathway can explain why some people nap more than others.”
Dashti said: "This tells us that daytime napping is biologically driven and not just an environmental or behavioral choice.”
"Future work may help to develop personalised recommendations for siesta.”
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