People missing out on much-needed sleep are not only less appealing to
Psychologists found back to back nights without the appropriate rest would be enough to encourage others to stay away.
"If someone looks less healthy, you are more likely to withdraw from them," Tina Sundelin, doctor and lead researcher at the Karolinska Institute in Stockholm, told The Guardian.
"If you can see someone hasn't slept, you'll have a good idea that they might not be the best person to be around," she added.
The researchers recruited 25 university students, some male and female, to take part in the sleep experiment. All of the paid volunteers were asked to measure their night time movements with specialist equipment each evening.
The volunteers photographed themselves, make-up free, after getting a good night's sleep for two consecutive nights before taking pictures once again after only having four hours sleep for two nights in a row the following week.
The Karolinska Institute then invited 122 strangers from Sweden's capital city to rate the photos of the participants on attractiveness, trustworthiness, health and sleepiness.
The results showed the strangers were able to capably