(ORDO NEWS) — Scientists continue to discover the ways in which lack of sleep affects our mental and physical health, and now a new study has shown that severe lack of sleep can even affect how we perceive other people.
When we don’t get enough sleep, we spend less time fixing our eyes on other people’s faces, according to research. Since this is so important for receiving social cues from the people around us, our relationships can suffer.
What’s more, angry faces appear less trustworthy and less healthy after sleep loss, while neutral or frightened faces appear less attractive than after a full night’s sleep.
“Because facial expression is critical to understanding other people’s emotional state, less time spent fixating on faces after acute sleep loss may increase the risk that you are inaccurate or too late in interpreting other people’s emotional state,” says sleep researcher Live. van Egmond from Uppsala University in Sweden.
The authors of the study recruited 45 participants who spent one night without sleep and the other with 8 hours of sleep, at least a week apart. In each case, eye-tracking sensors were used the next morning to track the gaze of the subjects as they looked at images of faces.
Various expressions were depicted on the faces: happy, angry, frightened, and neutral. Participants were also asked to rate the attractiveness, trustworthiness, and health of the faces they saw.
With regard to fixation on the face, there was a 6.3-10.6 percent decrease in fixation duration after sleep loss, and this decrease occurred regardless of which emotion was displayed. In general, faces were rated as less reliable and less attractive after a night without sleep.
“The fact that, in our study, sleep-deprived subjects rated faces with anger as less authentic and healthy, and neutral and frightened faces as less attractive, indicates that sleep loss is associated with more negative social impressions of others.” , says neuroscientist Christian Benedikt of Uppsala University.
“This can lead to decreased motivation for social interaction.”
It may not be surprising that lack of sleep makes us less likely to interact with other people, but this study adds some interesting data. Negative social impressions of people after sleep loss may lead to social withdrawal in those with sleep problems, the researchers suggest.
The research team also hypothesized that sleep deprivation, and the resulting less focus on faces, may cause problems judging the emotional state of others, a key part of maintaining social connections.
We already know that lack of sleep means we are less attentive and slower in interpreting emotions, which could be a contributing factor. However, to really understand what is going on, studies with large sample sizes over a long period of time are needed.
“Our participants were young adults,” says van Egmond. “We don’t know if our results can be generalized to other age groups. What’s more, we don’t know if similar results will be seen among those suffering from chronic sleep loss.”
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