Medical News, Sleep

MIT researchers find naps may be more beneficial than increasing night-time sleep

The researchers found that adding 30-minutes of sleep to one’s nightly routine had no meaningful impact on general well-being or work performance. However, the results indicated that taking a 30-minute nap during the day did improve cognition, energy, and overall well-being.

Sleep is a vital component to our health and well-being. Millions of individuals, however, do not get enough sleep, and studies show many suffer from sleep deprivation. According to NSF surveys from 1999 to 2004, at least 40 million Americans suffer from over 70 different sleep disorders, and 60% of individuals report sleeping issues a few evenings a week or more.

A large amount of research, largely conducted in sleep labs, shows that sleep deprivation has severe negative impacts on a variety of outcomes, ranging from attention and memory to mood and health. Among sleep scientists, there is a widely held belief that lowering sleep deprivation could lead to overall improvements in individual well-being and even better economic outcomes.

In a recently published study, researchers at MIT decided to investigate this phenomenon among overworked and underslept people in Chennai, India in hopes of finding which sleep techniques would best improve everyday life. 

Surprisingly, the researchers found that increasing sleep overnight by 30-minutes did not reveal significant effects on overall well being, nor better work outcomes. However, the team did find that one 30-minute nap during the day did significantly improve cognition, energy, and well being. 

The study outlined that these participants woke up on average 31 times each night. Despite being in bed for 8 hours, the subjects only averaged 5.5 hours of sleep. This, the authors hypothesized, may have been a major reason why increasing sleep overnight didn’t have an effect.

The paper’s results state, “Each of the night sleep treatments alone had no effect or a slightly negative (but insignificant) effect on participants… In contrast, participants in the nap only treatment experienced positive and marginally significant effects of 0.11 std. dev. (std. err. = 0.07, p = .11).”

Over a month’s time, 452 individuals from Chennai, India were examined each day and night. Researchers employed the help of actigraphs for each individual in order to examine their sleep patterns. An actigraph is a non-invasive device used to track rest/activity cycles. The device is also known as an actimetry sensor, and assesses gross motor activity. The device is commonly worn on the wrist in a wristwatch-like packaging.

“A key thing that stands out is that people’s sleep efficiency is low, that is, their sleep is heavily fragmented,” MIT’s Frank Schilbach stated. “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.” 

This study was able to be performed in the field, as opposed to being in a lab. Because of the actigraphs, the researchers were able to perform their experiments more accurately while in the homes of the participants.

Schilback added, “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 [company] savings. These two interventions have different effects.”

The researchers suggest that this research could be used to help employers maximize employee efficiency, such as through the development of better shift schedules.


The study was published in The Quarterly Journal of Economics, on April 8th, 2021.

Abstract. The urban poor in developing countries face challenging living environments, which may interfere with good sleep. Using actigraphy to measure sleep objectively, we find that low-income adults in Chennai, India, sleep only 5.5 hours a night on average despite spending 8 hours in bed. Their sleep is highly interrupted, with sleep efficiency—sleep per time in bed—comparable to those with disorders such as sleep apnea or insomnia. A randomized three-week treatment providing information, encouragement, and improvements to home sleep environments increased sleep duration by 27 minutes a night by inducing more time in bed. Contrary to expert predictions and a large body of sleep research, increased nighttime sleep had no detectable effects on cognition, productivity, decision making, or well being, and led to small decreases in labor supply. In contrast, short afternoon naps at the workplace improved an overall index of outcomes by 0.12 standard deviations, with significant increases in productivity, psychological well-being, and cognition, but a decrease in work time.

Pedro Bessone, Gautam Rao, Frank Schilbach, Heather Schofield, Mattie Toma, The Economic Consequences of Increasing Sleep Among the Urban Poor, The Quarterly Journal of Economics, Volume 136, Issue 3, August 2021, Pages 1887–1941, https://doi.org/10.1093/qje/qjab013

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