The study, led by researchers at Colorado College, found that those who were told they’d had a good night’s sleep, even if they hadn’t, outperformed those who were informed they’d slept badly.
The researchers told 164 participants that a new technique, which in fact does not exist, could measure their sleep quality from the night before.
They were randomly assigned to two groups -- “above average”-quality sleep and “below average”-quality sleep -- and then given a 5-minute lecture on how sleep quality can improve cognitive functions.
Regardless of how the participants originally felt about their sleep, those in the “above average” group were told that their sleep quality from the night before had been above average, whereas those in the other group were informed that theirs was below average.
Then, researchers measured the participants’ ability to listen to and process information. The people who were told they had slept well performed far better.
The phenomenon is thought to be a result of the placebo effect, which is normally known to occur in patients who are given inactive drugs and believe they work, leading to improvements in their health.
“These findings supported the hypothesis that mindset can influence cognitive states in both positive and negative directions, suggesting a means of controlling one’s health and cognition,” the research team concluded.
The study on the placebo sleep effect was published in the Journal of Experimental Psychology: Learning, Memory and Cognition.
By Ock Hyun-ju, Intern reporter (firstname.lastname@example.org)