You know the drill: You haven't had a good night's sleep for a few days and now you don't like what you see in the mirror - puffy eyelids, dark circles, sallow skin.
You splash some water on your face and hope no one notices. Besides, it doesn't really matter if you look tired, you tell yourself. It's not like anyone is going to notice, right?
It turns out that just two consecutive nights of restricted sleep can make you appear less attractive to others and, even worse, make them less interested in hanging out with you, according to a study in Royal Society Open Science.
"People seem to be able to tell when someone needs more sleep, and are more inclined to leave them alone in that case," the authors wrote in the new work.
To come to this conclusion the researchers recruited 25 volunteers who agreed to deliberately limit their sleep for the good of science.
Member of this group, referred to as "subjects" in the paper, had their photo taken twice - once after two consecutive nights of normal sleep (about 7.5 hours) and again after two consecutive nights of poor sleep (about 4.25 hours).
In both sets of pictures the subjects were photographed in a gray T-shirt, with their hair pulled away from their faces, and were told not to wear makeup.
Next, the researchers showed the photos to a different set of 122 volunteers they called "raters." These people were asked to rate the subjects on attractiveness, health, sleepiness and trustworthiness.
They also were asked how much they would like to socialize with the person in the photo.
The study authors found that overall, raters were less willing to socialize with tired-looking subjects compared with those who were well rested.
In addition, they also deemed the poorly rested subjects to be less attractive, less healthy and more sleepy compared to when they were well rested.
"Telling someone they look tired says more about your perception of them than you might think," the authors wrote.
The study did not address the reason that a lack of sleep makes others want to avoid you, but the authors have a hypothesis. They explain that blood flow to the skin is strongly promoted by sleep. Perhaps when we don't get enough sleep, that results in restricted blood flow to the skin, which in turn would make us look more pale and tired.
"We're still not sure about this," said Tina Sundelin, a post-doctoral student in psychology at both the Karolinska Institutet in Sweden and New York University who led the work. "Hanging and swollen eyelids is probably due to something other than blood flow, but we haven't looked into that yet."
She added that not everyone looks worse after a few nights of bad sleeping.
"For some participants, it was very clear which condition the photo belonged to, and for others, there was virtually no difference between the two," Sundelin said. "A couple of participants were even rated as more attractive after sleep restriction."
And here's another piece of good news: Sundelin said that coffee and makeup might help a person look more awake.
"Something as easy as smiling might help," she said. "A 2013 study indicated that sleep-deprived people look a bit more sad, so smiling more may further counteract the effects of looking tired."
It's good to know you've got options if you've had a few rough nights, but Sundelin still encourages you to prioritize getting more sleep.
"That gives other benefits as well," she said.
Explore further: Study reveals the face of sleep deprivation
Tina Sundelin et al. Negative effects of restricted sleep on facial appearance and social appeal, Royal Society Open Science (2017). DOI: 10.1098/rsos.160918