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Too little sleep makes you less attractive

If you get enough sleep you will be more attractive than if you don't get enough. Researchers at the Swedish Karolinska Institutet have proved this once and for all after doing an experiment in which they got young adults to sleep too little one night, followed by a night with no sleep at all.

The researchers used 23 healthy men and women aged between 18 and 31. On the first night they were only allowed to sleep for 5 hours, and then they were kept awake for another 31 hours. At the end of the time the researchers took a photo of the subjects' faces. The Swedes then showed the photos to a panel of 65 students, who then had to give scores for how attractive, healthy or tired the subjects looked.

The researchers had also taken a photo of the 23 subjects when they had had enough sleep. The panel were shown these as well, making a total of 46 photos for them to look at.

An example of a pair of photos is shown below. The photo on the left is of the person who has had enough sleep, and the one on the right of the same person, but sleep deprived.

Too little sleep makes you less attractive

The panel had to give the people in the photos a score between 0 and 10 for attractiveness, tiredness and health.

Sleep deprivation made the subjects first of all look more tired, and in the second place less healthy. In third place came unattractiveness.

Too little sleep makes you less attractive

The judgements that the researchers measured influence each other. The healthier someone looked, the more attractive they were also perceived to be. Appearing to have had enough sleep weighed less heavily as a factor.

Too little sleep makes you less attractive

The researchers think that preference for a well-rested face is a result of the evolutionary process. People who sleep well are healthier, and their children are therefore likely to be stronger.

So if you notice that wearing a red outfit just isn't enough, now you know what to do. Throw your alarm clock out of the window.

BMJ 2010;341:c6614.

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