If you want to look attractive and healthy, the best thing you can do is get a good night's sleep, finds research in the Christmas issue published on the British Medical Journal website.

For the first time, say the authors, there is scientific backing for the concept of beauty sleep.

The study, led by John Axelsson from the Karolinska Institutet in Sweden, investigated the relationship between sleep and perceptions of attractiveness and health. The authors believe this research is important in today's 24 hour society with the number of people suffering from sleep disorders and disturbed sleep on the rise.

Twenty-three participants between the ages of 18 to 31 took part in the study. They were photographed between 2pm and 3pm on two occasions, once after normal sleep and once after being deprived of sleep. Smokers were excluded from the research and no alcohol was allowed for two days prior to the experiment.

The photographs were taken in a well-lit room and the distance to the camera was fixed. During both photography sessions participants wore no make-up, had their hair loose (combed back if they had long hair) and underwent similar cleaning or shaving procedures. They were asked to have a relaxed, neutral facial expression for both photos.

Sixty-five observers, who were blinded to the sleep status of the subjects, rated the photographs for attractiveness and whether the individuals looked healthy/unhealthy or tired/not tired.

The observers judged the faces of sleep-deprived participants as less healthy, less attractive and more tired.

The authors conclude that the facial signals of sleep deprived people affect facial appearance and judgments of attractiveness, health and tiredness.