SALT LAKE CITY (ABC4) – A new study may take the guilt out of wanting to take a nap.

Many animals who are awake during the day and sleep at night take naps. Dogs, flies, and people. But what makes some people morning people, night people, and nap people?

New research suggests it may be in your genes – especially the urge to take a nap.

Call it what you will, a power nap, a siesta, or just an afternoon dropout. Researchers have learned that people who like to take naps share some genetic traits that may make them enjoy naps.

In the largest study of its kind, a team led by Harvard Investigators at Harvard-affiliated Massachusetts General Hospital (MGH) collaborated with colleagues at the University of Murcia in Spain and several other institutions then published in Nature Communications.

The study says, “Naps are short daytime sleep episodes that are evolutionarily conserved across diverse diurnal species ranging from flies to polyphasic mammals. In human adults, daytime napping is highly prevalent in Mediterranean cultures and is also common in non-Mediterranean countries including the United States”

The study discovered dozens of gene regions that govern the tendency to take naps during the day.

In a statement to the Harvard Gazette, “Napping is somewhat controversial,” says Hassan Saeed Dashti of the MGH Center for Genomic Medicine, co-lead author of the report with Iyas Daghlas, a medical student at Harvard Medical School (HMS). Dashti notes that some countries where daytime naps have long been part of the culture (such as Spain) now discourage the habit. Meanwhile, some companies in the United States now promote napping as a way to boost productivity.

“It was important to try to disentangle the biological pathways that contribute to why we nap,” says Dashti.

Researchers first used the UK Biobank data for the GWAS (genome-wide association study), which holds the genetic information on 452,633 people. The participants were asked whether they nap during the day “never/rarely,” “sometimes,” or “usually.”

Some of the participants wore accelerometers to monitor their activity during the day.

The accelerometers helped the researchers determine if the responses from the people matched with activity. “That gave an extra layer of confidence that what we found is real and not an artifact,” says Dashti.

The team discovered certain genes play a factor, according to the results posted in the Harvard Gazette. People who needed naps expressed the need and the reason why differently.

The study says, “Genetic variation constitutes an important contributor to inter-individual differences in napping preference. A twin study estimated heritability of self-reported napping and objective daytime sleep duration to be 65% and 61%, respectively, demonstrating heritability similar or even higher than heritability found for other sleep traits such as nighttime sleep duration and timing”

Once they dug into the data the team discovered different mechanisms in each of us that promotes napping.

  • Sleep propensity: Some people need more shut-eye than others.
  • Disrupted sleep: A daytime nap can help make up for poor quality slumber the night before.
  • Early morning awakening: People who rise early may “catch up” on sleep with a nap.

What does it all mean? They all needed naps.

“This tells us that daytime napping is biologically driven and not just an environmental or behavioral choice,” says Dashti.