A new study has suggested yet another reason why a good night's sleep is important: it makes you more attractive.
Researchers in Sweden found that those who lacked proper sleep looked more unhealthy, were paler, had red eyes and suffered more wrinkles.
The study saw researchers photograph 10 participants on two occasions, the first time after a good night's sleep and the second when participants had been awake for 31 hours.
Forty people were asked to rate the pictures on a number of criteria, including how sad, tired and attractive the subjects looked.
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The findings were obvious: the more tired someone was, the less attractive they appeared.
The puffiness around the eyes and redness were enough to make someone unattractive, or at least less attractive, but a droopier mouth, fine lines and hanging eyelids also negatively contributed.
"Since faces contain a lot of information on which humans base their interactions with each other, how fatigued a person appears may affect how others behave toward them," study author Tina Sundelin said in a press release.
"This is relevant not only for private social interactions, but also official ones such as with health care professionals and in public safety."
The study was published in the aptly named journal Sleep.