How Sleep Deprivation Changes the Way You See Other People

how sleep deprivation affects social interactions

Young adults when sleep-deprived evaluate angry faces as less trustworthy and healthy-looking. Furthermore, neutral and fearful faces appear less attractive following sleep loss, suggests the findings of a new study from Uppsala University.

Using eye-tracking, a sensor technology that can detect what a person is looking at in real-time, researchers from Uppsala University in Sweden performed an experiment on 45 young men and women to examine how acute sleep loss affects the way humans explore and evaluate happy, fearful, angry and neutral faces. The participants spent one night with no sleep and one with an eight hour sleep opportunity. Their eye movements were measured in the mornings following both nights.

"When sleep-deprived, our research subjects spent less time fixating on faces. Since facial expressions are crucial to understanding the emotional state of others, spending less time fixating on faces after acute sleep loss may increase the risk of interpreting the emotional state of others inaccurately or too late," said Lieve van Egmond, first author and PhD student in the Department of Surgical Sciences at Uppsala University.

"The finding that sleep deprived subjects in our experiment rated angry faces as less trustworthy and healthy-looking and neutral and fearful faces as less attractive indicates that sleep loss is associated with more negative social impressions of others. This could result in less motivation to interact socially," added senior author Christian Benedict, Associate Professor of Neuroscience.

Sleep Loss Can Alter the Way We Perceive Others, Study Finds

Lack of sleep doesn’t just make us tired—it can significantly change how we see and judge the people around us. A new study from Uppsala University in Sweden reveals that sleep deprivation negatively affects how young adults perceive facial expressions, potentially influencing social interactions and relationships.

How Sleep Deprivation Affects Social Perception

According to the research, young adults who were sleep-deprived perceived angry faces as less trustworthy and less healthy-looking. In addition, neutral and fearful faces appeared less attractive after a night without sleep. These findings suggest that sleep loss may cause people to form more negative impressions of others, even when those impressions are not accurate.

Inside the Study: Eye-Tracking and Facial Evaluation

The study involved 45 young men and women who participated in two experimental conditions:

• One night with no sleep.
• One night with an eight-hour sleep opportunity.

Researchers used eye-tracking technology, a sensor-based method that records where and how long a person looks at specific features in real time. Participants were shown images of happy, fearful, angry, and neutral faces, and their eye movements were measured the following morning after each sleep condition.

Less Focus on Faces After Sleep Loss

One of the key findings was that sleep-deprived participants spent less time fixating on faces overall. This is significant because facial expressions play a vital role in understanding emotions and intentions.

“When sleep-deprived, our research subjects spent less time fixating on faces,” said Lieve van Egmond, first author and PhD student at the Department of Surgical Sciences, Uppsala University.

“Since facial expressions are crucial to understanding the emotional state of others, reduced attention may increase the risk of misinterpreting emotions or reacting too late.”

Negative Impressions and Reduced Social Motivation

The researchers also found that sleep deprivation led to more negative social evaluations. Angry faces were judged more harshly, while neutral and fearful faces were seen as less appealing.

“These findings indicate that sleep loss is associated with more negative social impressions of others,” explained Christian Benedict, Associate Professor of Neuroscience and senior author of the study.

“This could ultimately reduce motivation to engage in social interactions.”

Why Getting Enough Sleep Matters

This research highlights the importance of healthy sleep habits, not only for physical and mental health but also for social functioning and emotional intelligence. Chronic sleep loss may increase misunderstandings, reduce empathy, and strain personal and professional relationships.

Key Takeaway

Getting enough sleep helps us read social cues accurately, form fair impressions, and maintain healthy social connections. Prioritizing sleep could improve not just how we feel—but how we relate to others.

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