Stress can make you seem less attractive, a study found.
Behavioural expert Dr Fhionna Moore examined how mental and emotional strain can affect the way someone's physical appearance is perceived.
Her research revealed men and women become significantly more attractive to potential partners if they have lower tension levels than their rivals.
Reduced attractiveness was attributed to the anxiety hormone cortisol, which increases the amount of glucose floating around the body while also inhibiting muscle and bone growth.
The overall impact is that stressed individuals appear less healthy, and therefore "uglier".
Dr Moore, a lecturer in psychology at Dundee University, conducted several investigations into the effect.
She said: "In one study we measured levels of cortisol from saliva samples and took photographs of the faces of our participants.
"Cortisol is an interesting hormone because it is released when we deal with a stressor, and allows us to cope in the short term. But if it's elevated for longer periods... it can be very bad for our health.
"We found that the faces of men and women who had high levels of cortisol in their saliva were rated as less attractive and healthy than those with lower levels of cortisol."
She added that traits linked to attractiveness often indicate good health.
These include face symmetry because a strong immune system is needed to "develop evenly on both sides", and colour in the skin suggesting "a healthy diet and good cardiovascular health".
- Daily Mail