A daytime nap helps increase productivity than night sleep: study

Our Bureau New Delhi | Updated on July 30, 2021

Long naps were linked to elevated risk of death only in those who slept more than six hours per night.

Massachusetts Institute of Technology researchers carried out a study on low-income workers in Chennai.

In an interesting study, researchers have shown that a daytime nap rather than a night sleep of a longer duration would be more beneficial in increasing the productivity of people.

In a study carried out on over 450 low-income workers in Chennai, a team of researchers from the Massachusetts Institute of Technology (MIT) in the US-led by economist Frank Schilbach increasing the sleep time of people did not confer any benefits in work productivity, earnings, sense of well-being or even lowered their blood pressure.

On the other hand, short daytime naps improved their productivity and well-being, the researchers reported in a paper to be published in August in the Quarterly Journal of Economics.

Chennai study

The study had its genesis in another research that Schilbach and his colleagues in Chennai — during which they have observed that low-income people tend to have difficulty sleeping circumstances in addition to their other daily challenges.

To conduct the latest study, the researchers equipped Chennai residents with actigraphs. These wristwatch-like devices that infer sleep states from body movements, which allowed the team to study people in their homes.

The study examined 452 people over a month. Some people were given encouragement and tips for better sleep; others received financial incentives to sleep more. Some members of both those groups also took daytime naps to see what effect that had.

The participants in the study were also given data-entry jobs with flexible hours while the experiment was taking place, so the researchers could monitor the effects of sleep on worker output and earnings in a granular way.

Key findings

Overall, the Chennai study’s participants averaged about 5.5 hours per night before the intervention and added 27 minutes per night on average. However, to gain those 27 minutes, the participants were in bed an extra 38 minutes per night. Interestingly, the researchers found out that the participants, on average, woke up 31 times per night.

“A key thing that stands out is that people’s sleep efficiency is low, that is, their sleep is heavily fragmented,” Schilbach, who is the Gary Loveman Career Development Associate Professor of Economics at MIT, said in a statement.

Other authors of the study included Pedro Bessone, a recent graduate from MIT’s Department of Economics and Gautam Rao, an associate professor of economics at Harvard University.

“They have extremely few periods experiencing what’s thought to be the restorative benefits of deep sleep. … People’s sleep quantity went up due to the interventions, because they spent more time in bed, but their sleep quality was unchanged,” he said.

That could be why people in the study experienced no positive changes after sleeping more across a wide range of metrics. Indeed, as Schilbach notes, “We find one negative effect, which is on hours worked. If you spend more time in bed, then you have less time for other things in your life.”

On the other hand, study participants who were allowed to nap while on the data-entry job fare better in several measured categories.

“In contrast to the night sleep intervention, we find clear evidence of naps improving a range of outcomes, including their productivity, their cognitive function, and their psychological well-being, as well as some evidence on savings,” Schilbach, who is also a faculty affiliate at MIT’s Abdul Latif Jameel Poverty Action Lab (J-PAL), said. “These two interventions have different effects.”

That said, naps only increased total income when compared to workers who took a break instead. Naps did not increase the total income of workers — nappers were more productive per minute worked but spent less time working.

“It’s not the case that naps just pay for themselves,” Schilbach said. “People don’t actually stay longer in the office when they nap, presumably because they have other things to do, such as taking care of their families. If people nap for about half an hour, their hours worked falls by almost half an hour, almost a one-to-one ratio, and as a result, people’s earnings in that group are lower.”

Published on July 30, 2021

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