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What role does eye color play in winter depression?
The psychologist Prof. Lance Workman from the University of South Wales examined the connection between winter depression and the eye color of those affected for a study of seasonal affective disorders with 175 participants. The study participants were students from Wales and Cyprus. Amazingly, he was able to show that people with brown and very dark eyes are significantly affected by winter blues and seasonal depression. People with blue eyes or generally light eye color suffer less often from winter depression.
What sounds unbelievable at first can be scientifically justified. The cells in the retina of our eyes not only send optical signals to the brain to produce images. Some retinal cells are solely responsible for transmitting information about the perceived brightness from the eye to the brain. When it gets dark, these cells send the information “Caution, the brightness is decreasing” to the hypothalamus, in which the sleep hormone melatonin is then produced. Just as light skin is more sensitive to the sun’s rays, light eyes are significantly more sensitive to light. Lightly pigmented eyes are also more sensitive to light than more heavily pigmented dark eyes.
In his study, Prof. Workman proves that light-colored eyes, because they are more sensitive to light, absorb more light than dark eyes, even on typical dim and cloudy winter days. So melatonin production in winter is lower in people with light eyes than in dark-eyed people. The disruption of the day-night rhythm, which seems to be the cause of winter blues, is therefore not as severe in people with blue and light eyes. They experience less winter blues or seasonal depression.
