Researchers from the University of South Wales (USW) have discovered that people with brown eyes are more likely to suffer from the so-called “seasonal affective disorder” (SAS), which – although it can also occur in summer – usually manifests more in autumn or winter, so it is also known as winter depression.

The results of this new study were presented on Thursday at the annual conference of the British Psychological Society (BPS) in the English city of Nottingham.

The scientists came to this conclusion after polling 175 students from the USW and the Girne American University in North Cyprus, and did not find a direct correlation between the differences in their moods and the different geographical origins, although they did find a variation in the color of the the eyes.

Less light in the brain

The reason why people with brown eyes are at greater risk of becoming ‘victims’ of winter depression lies in melatonin , whose levels are reduced by the entry of light into the brain.

“Because more light enters the brain through blue eyes, this may lead to a greater melatonin reduction during the day, so that people with lighter eyes are less likely to have seasonal affective disorder”, explains Professor Lance Workman.

Scientists have also found that the incidence in women of seasonal depression is 40% higher than in men . This data is derived from another study presented in the same conference conducted on the basis of an online survey of 2,031 adults. For every 100 men with seasonal affective disorder there were 140 women with the same problem.

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