(LONDON) -- Did you get your beauty rest last night?
Swedish researchers say there's an important link between sleep and your physical appearance. In a study published Wednesday in the British Medical Journal, researcher John Axelsson and his team at the Karolinska Institute in Stockholm found that sleep-deprived individuals appear less healthy, more tired, and less attractive than those who have received a full night's worth of sleep.
"Sleep is the body's natural beauty treatment," Axelsson said. "It's probably more effective than any other treatment you could buy."
In the study, 23 healthy adults from ages 18-31 were first photographed after eight hours of sleep, wearing no makeup. The same adults were photographed again after sleeping only five hours and being kept awake for a full 31 hours, with the same lighting and camera settings.
The photos were rated by 65 untrained observers who graded the images in these three categories -- how healthy, attractive, and tired the individuals appeared. On the whole, the participants were judged to be worse-off after sleep deprivation, in all categories, and the scientists believe the effects would be even more dramatic in person, when factors like blink rate and drowsiness could be observed.
Only one photo set was publicly released from the sample, showing a young man. After sleep deprivation, his eyes seem duller and the skin under his eyes appear puffy.
While the effects in Axelsson's research were observed after severe sleep deprivation, he says his team will soon tackle whether an occasional short night of sleep can also cause problems. This experiment called for severe deprivation because the scientists wanted to maximize any effects.
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