Cold weather and longer nights have a negative effect on many of us, resulting in irritability and lethargy in the winter months. Called Seasonal Affective Disorder (SAD), this phenomenon is a recognised form of clinical depression, although experts are divided on the causes.

Lance Workman, Visiting Professor in Psychology at The University of South Wales, firmly believes that certain individuals have a genetic predisposition to SAD based on eye colour. Though many people might suspect they have SAD, the condition is usually diagnosed using the seasonal pattern assessment questionnaire. This asks people to answer a number of questions about seasonal behaviour, mood and habit changes.

In a study based on a sample of 175 students from two universities (one in south Wales, the other in Cyprus), Professor Workman found that people with light or blue eyes scored significantly lower on the seasonal pattern assessment questionnaire than those with dark or brown eyes. These results agree with previous research which found that brown or dark-eyed people were significantly more depressed than those with blue eyes.

One hypothesis is that, as eyes with less pigment are more sensitive to light, they don’t need to absorb as much light as darker eyes before this information reaches the retinal cells. As such, people with lighter eyes release less melatonin during autumn and winter. This mechanism might provide light-eyed people with some resilience to seasonal affective disorder, making them feel a little cheerier in the depths of winter.

Sources:

1.Yahoo! News:
Seasonal affective disorder: your eye colour might be why you have the 'winter blues' .

2.You Magazine:
Your eye colour could be the reason that you have seasonal affective disorder.