Want to appear intelligent? Get more sleep!

London: Getting a good night's sleep may not only remove your tiredness, but also make you appear more intelligent, according to a new study.

Researchers at the University of St Andrews in the UK have found that getting enough sleep may help individuals appear more intelligent to their teachers and prospective employers by influencing their neutral expression.

The research sheds light on how people may change their perceived intelligence regardless of their attractiveness, and it appears the answer lies in the neutral facial expression.

Using special face-processing software, researchers measured the degree of eyelid openness and mouth curvature of 190 faces (children and adults), who were photographed with a 'neutral expression.'

Over 200 evaluators were then asked to rate the attractiveness and intelligence of the faces - the results show that those faces with a subtle frown and droopy eyes were perceived as less intelligent.

"Attractive people are often perceived as more intelligent, but we wanted to investigate how individuals can change their perceived intelligence, regardless of their attractiveness," said Sean Talamas from University of St Andrews.

"The solution seems to lie in subtle differences in a resting facial expression that are related to sleep - namely eyelid droopiness and subtle frowning," said Talamas.

In collaboration with researchers at the Karolinska Institutet in Sweden, photographs were also taken of the same participants after a full night's sleep and after a night of restricted sleep.

When the same individuals had less eyelid-openness and a subtle frown it resulted in a significant decrease in their perceived intelligence.

"Recent scientific advances show how subtle expressions affect judgements but our work is new in demonstrating the impact of apparent tiredness on social judgements. Sleep is not just important for performance but it also affects how others see us," said David Pierrette from University of St Andrews.

"The take home message? In an interview with an employer or the front row of a classroom, being cautious of your resting facial expression and getting more sleep may help you look more intelligent," Talamas added.

The findings were published in the Journal of Experimental Psychology: General.