When women say they need their beauty sleep, they might just be right.
A study has found that losing just a few hours of sleep really does make females less attractive.
Having four hours of sleep – the amount famously taken by Margaret Thatcher – makes women appear less attractive and more unhealthy, according to a study in which people were asked to grade photographs of women who had suffered two nights of restricted sleep.
The findings, which will concern night owls and mothers unable to get their full eight hours, show how important sleep is to physical beauty. In the study, photographs were taken of 25 women after two nights in which one group slept about seven and a half hours and the others for an average of four hours and 15 minutes.
When 122 people were asked to rate the subjects’ attractiveness on a seven-point scale, those with less sleep came out 0.2 points lower.
The study’s co-author, Professor John Axelsson, from Stockholm University, said the research confirmed that beauty sleep was an appropriate saying and added: "The effects of tiredness on attractiveness are not large but they can make a difference to many aspects of life."
He said people in the study were less keen to socialise with the tired women. "If someone looks tired, they look less interested in being with you and as if they would rather be asleep or alone," said Professor Axelsson.
"They are a risk factor, in that they probably won’t be as good at collaborating and could make mistakes or cause accidents."
He added that sleepless people could even appear more sad "as the mouths of tired people droop even when we tell them to appear neutral".
A degree of redness in the face is known to be judged healthy and attractive and a lack of sleep reduces blood flow, leaving tried people looking pale.
The study concludes: "Raters were much more willing to socialise with someone they considered attractive than someone unattractive, and attractive people looked substantially healthier."
Previous studies have shown that people who are sleep-deprived are less optimistic and sociable, worse at understanding and expressing emotions and are more accident-prone.