How Well People ‘Think’ They Slept Might Matter More Than How They Actually Slept

A new study finds a connection between how satisfied a person is with their previous night’s sleep and their feelings of well-being the next day

How satisfied people are with their night’s sleep has a major impact on how well they feel the next day, regardless of what a tracking device might indicate about the quality of that sleep.

So says a new study conducted by researchers from the University of Warwick in England. The research involved 109 university students ages 18 to 22 who took part in a two-week study.

The students wore wrist devices that used movement to estimate their sleep efficiency, or the amount of time they were asleep during the period between the time they were ready to fall asleep (for example, if someone is reading a book in bed and then puts it away) and the time they woke up.

Study participants also used smartphones to answer questions about their previous night’s sleep and their well-being on the current day.

Once a day, participants were asked five questions on a mobile-phone application: what time they went to bed, what time they were ready to fall asleep, what time they woke up, what time they got out of bed and how satisfied they were with their sleep. Information from wrist-worn devices that measured sleep quality wasn’t visible to the students.

Five times a day, at random times, participants were asked how they were feeling at that moment and answered the questions on the same mobile app. Questions were about their moods and about how satisfied they were with their lives.

Findings showed that self-reported sleep satisfaction was consistently linked to well-being. The better a student reported to have slept, the better their mood and satisfaction with life was the next day. By contrast, the information provided by the sleep device wasn’t associated with the students’ reported well-being the next day. 

“It is people’s evaluations of their sleep quality and not the actigraphy-derived [device-derived] sleep efficiency that’s important to their well-being,” says Anita Lenneis, psychologist and honorary research fellow at the University of Warwick and lead author of the study. The results suggest that thinking more positively about one’s sleep might increase well-being, says Lenneis, who adds that it isn’t uncommon for a person to report feeling refreshed in the morning even if a sleep tracker indicates something different.

There were some limitations to the study’s findings, Lenneis says. For one, the homogenous study group makes it impossible to generalize results to a broader adult population. In addition, wrist-worn devices don’t measure sleep exactly, but rather the movements that are used to estimate sleep. Additionally, because participants had 24 hours to answer questions about a previous night’s sleep, that amount of time could have influenced memory and thus influenced the findings.

What is most important, says Neomi Shah, program director of sleep medicine at Icahn School of Medicine at Mount Sinai in New York, is to pay attention to how you feel about your sleep instead of looking at what devices say. In fact, the study could infer that wearables and technology might negatively affect well-being in some individuals, adds Shah, who wasn’t involved in the research.

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