Get enough sleep is an essential building block for staying fit and healthy, which is why scientists are constantly looking to explore the realm of sleep. A common idea is that sleeping as long as possible seems to bring great benefits: many people find that it gives them more energy and a better sense of well-being. But a new study co-authored by economists at MIT and published in “The Quarterly Journal of Economics” suggests that in reality, pass a few extra hours in bed is not beneficial to the body, if there is not also a corresponding increase in good quality sleep.
The research involved 452 low-income workers over the course of a month in Chennai (India) who agreed to wear actigraphs, small portable motion sensors capable of monitoring sleep cycles while people are sleeping at home, without the need for additional equipment. By providing tips for better sleep and improving home sleep environments, the researchers were able to get participants to sleep for nearly a day. extra half hour each night on average, but the expected benefits in terms of productivity at work, feelings of well-being or even better blood pressure did not follow.
“The quality of their sleep has not changed”
“To our surprise, these interventions had no positive effect on any of the outcomes we measured. », Explains Frank Schilbach, economist at MIT. Overall, participants slept an average of 5.5 hours per night out of 8 hours spent in bed before the study and subsequently received an average of 27 additional minutes of sleep. However, in order to gain those 27 minutes, the participants were in bed an additional 38 minutes per night, which is indicative of their difficult sleeping conditions. What’s more, participants woke up an average of 31 times per night: although the length of their nights or increased, these were always fragmented.
“A key element that stands out is that sleep efficiency was low. They have extremely little time to experience the restorative benefits of deep sleep. The amount of sleep increased due to the interventions as they spent more time in bed, but the quality of their sleep did not change. Adds Frank Schilbach. These results therefore suggest that helping people sleep more soundly, rather than just adding time to their total amount. poor quality sleep might be helpful. “Adding in poor quality sleep may not have the benefits that an extra half hour of sleep would have if it were of better quality. ”
A nap more beneficial than a bad hour of extra sleep in the evening
This paradoxical situation explains why, across a wide range of measures, people in the study did not experience any positive change. after sleeping more. This habit would even have a negative consequence during the day: a reduced number of hours worked. As the researchers attest, “We find a negative effect on hours worked because if you spend more time in bed, you have less time for other things in your life. “But the scientific team affirms that it is nevertheless possible to improve one’s sleep since during the study period, some participants also takes naps during the day, to see what effect it had.
And it turns out that those who were allowed to take a half-hour nap during their work time did better in several measured categories. “Unlike the intervention on nighttime sleep, We find clear evidence that naps improve a range of outcomes, including productivity, cognitive function, and psychological well-being. », Concludes Frank Schilbach. The scientific team calls for further studies in this area, which should focus on the quality of sleep rather than over time, and take better account of psychological factors, such as stress, often encountered by low-income families.