Not getting enough sleep may crimp your social life as well as take a toll on your looks, according to a new study from Sweden.
The study found that after only two nights of shorter-than-normal sleep, people are not only viewed by others as being less attractive and less healthy than after they are fully rested, they are also seen as less appealing to socialize with.
The effect of sleep deprivation on other people’s desire to socialize with that person was small, but still significant, according to the study’s authors.
“The importance of assessing evolutionarily relevant social cues suggests that humans should be sensitive to others’ sleep history, as this may indicate something about their health as well as their capacity for social interaction,” the study’s authors conclude.
“Recent findings show that acute sleep deprivation and looking tired are related to decreased attractiveness and health, as perceived by others,” they add. “This suggests that one might also avoid contact with sleep-deprived or sleepy-looking, individuals as a strategy to reduce health risk and poor interactions.”
For the study, researchers from the Karolinska Institute and Stockholm University recruited 25 healthy students, aged 18 to 47 (although most were in their early 20s). The students had their photos taken twice: after two nights of normal sleep and after two nights of restricted sleep. On average, the students slept a total of seven hours less over the two restricted-sleep sessions. Special monitors were used to verify their sleep time.
In the photos, which were taken at the same time of day, the students wore no make-up and their hair was pulled back.
The photos were then shown on a computer in random order to 122 residents of Stockholm, a group almost evenly divided by gender. These volunteers were asked to use a seven-point scale to rate the person shown in each photo on the following:
- how attractive they were
- how healthy they looked
- how sleepy they looked
- how trustworthy they looked
- how much they would like to socialize with them
The study found that most people’s ratings fell within the middle of the scale. But there were small differences in the ratings depending on whether the photo showed a person rested or sleep deprived.
The ratings for the photos taken after two nights of too little sleep were, on average, 0.09 points lower for attractiveness, 0.11 points lower for health and 0.25 points lower for sleepiness, compared with the ratings taken after two nights of normal sleep. No difference was found in the trustworthiness scores.
The study’s volunteers also indicated they were less willing to socialize with people who were sleep deprived — by an average of 0.15 points.
Why would we — apparently, unconsciously — want to avoid people who get too little sleep? “The reasons for avoiding people who look sleepy may include the fact that sleepy individuals are at a higher risk for accidents, or more prone to be carriers of contagious pathogens, or aspects making them less socially rewarding to be around,” the researchers explain.
Limitations and implications
The study has several limitations. Most notably, it involved only a small number of participants, and most of the people in the photos were healthy, white students in their twenties. The results might have been quite different if people of various ages, races and ethnicities had been included.
Furthermore, the study found that people’s willingness to socialize with sleep-deprived people was only 2.1 percent less than their willingness to do so with fully rested people. Just how significant such a small effect would be in a real-world social setting is not clear.
Still, the findings are interesting — if only as a reminder of the many ways that not getting enough sleep can negatively affect your wellbeing, including, apparently, your social wellbeing.