As our society becomes more global and active 24 hours per day, the number of people suffering from sleep disorders, disturbed sleep, and forced to adopt unnatural sleeping patterns has grown considerably, the authors explained.
John Axelsson and team set out to determine whether there might be a link between perceptions of attractiveness and health, and sleep.
Their study involved 23, non-smoking, young adult volunteers, aged between 18 and 31. They were photographed twice, each time between 2pm and 3pm. The first photograph was taken after they had had a good night's sleep, while the second one showed what they looked like after sleep deprivation.
All pictures were taken in the same, well-lit room, with a fixed camera and at a fixed distance. None of the participants wore make-up, their hair was combed back, and had undergone similar shaving and washing procedures before each photograph was taken. The photographer asked them to assume a neutral, relaxed facial expression on both photo shoots.
For a period of 48 hours before the study began, the participants were not allowed to consume alcohol.
Sixty-five other people were asked to rate the photographs for attractiveness, health aspect, and whether or not the person looked tired. The photograph observers did not know the sleep status of the participants they were asked to rate.
The authors reported that in the vast majority of cases, the observers rated those who had had a good night's sleep as more attractive, healthier, and with more vigor, compared to the ones in which they had been deprived of sleep.
The researchers concluded:
"This suggests that humans are sensitive to sleep related facial cues, with potential implications for social and clinical judgments and behaviour.
Studies are warranted for understanding how these effects may affect clinical decision making and can add knowledge with direct implications in a medical context."
John Axelsson, Tina Sundelin, Michael Ingre, Eus J W Van Someren, Andreas Olsson, Mats Lekander
BMJ 2010; 341:c6614 doi: 10.1136/bmj.c6614 (Published 14 December 2010)