Seasonal Affective Disorder (SAD), a mental health disorder, is often characterized by feelings of hopelessness and acute sadness that occur during the autumn and winter months.A form of depression, SAD is estimated to affect 5 percent of the United States population. And of these, women are thought to be at a higher risk, with almost 80% of those suffering from SAD being women.
Previously, researchers had discovered that a strong prevalence of SAD among women is not dependent on social or lifestyle factors, hinting that there could be biological sex-specific differences that may cause this high incidence rate in women.
Recent research is confirming this finding and adds an additional interesting element to the recipe. It seems eye color is an additional factor for predicting incidence of SAD.
Two new studies are providing interesting explanations about sex and eye color influencing the risk of SAD.
These findings were presented at the British Psychological Society conference in Nottingham, United Kingdom. Presented by Lance Workman, a professor at the University of South Wales in an interesting study titled: “Why blue eyes keep the blues away’.
They investigated the relationship between SAD, lateralized emotions, and eye color by surveying 175 trainees from the University of South Wales and the Girne American University in North Cyprus. The results of the surveys revealed that participants with brown eyes were considered most likely to experience shifts in mood compared to blue-eyed participants. Prof. Workman has an interesting explanation for this. He says,” We know that light entering the brain triggers a reduction in levels of melatonin. ”
“As blue eyes enable more light into the brain, it may be that this leads to a greater reduction in melatonin during the day and this is why people with lighter eyes are less prone to SAD.”
– Prof. Lance Worker
“Individuals with blue eyes appear to have a degree of resilience to SAD,” explained the authors of the study.
This, they posit, “may be taken as suggestive that the blue eye mutation was picked as a protective aspect from SAD as sub-populations of human beings migrated to northern latitudes.”
Individuals with SAD use their right brain
The group also asked the participants with SAD to take part in an extra test that analyzed how their 2 brain hemispheres responded when they were trying to recognize a range of emotional expressions on other person’s faces. This test hints that individuals with SAD tended to use their left visual field when recognizing facial expressions and utilize their brain hemisphere to “decipher” these expressions.
As Prof. Workman discusses,”This tendency to use the left visual field and right side of the brain for determining facial expressions exists in the general population, whether they have SAD or not.” But,” he continues, “individuals who [have] more traditional kinds of depression usually lose this best hemisphere advantage.”
“In the case of SAD, we discovered this left visual field benefit was in fact increased. This suggests SAD has various causes than, say, bipolar depression, ” adds Prof. Workman.
Why females may be at a greater risk
The second study presented at the conference surveyed a much bigger sample of 2,031 people. Of these, 8 percent had a persistent form of SAD, while 21 percent had a milder type of the illness.
Women were at an especially high risk – in reality, they were 40 percent more most likely to develop the condition than males. The study also explains that SAD symptoms are more harsher when women are of reproductive age.
This made Prof. Workman endeavor another possible evolutionary explanation for the findings. He speculates that the disorder is absolutely nothing but an energy-preserving mechanism gone haywire.
During a lady’s reproductive years, he says, the mom would need to conserve energy to make sure survival of both her and her offspring, especially throughout the winter months.
This appears to be supported by the reality that signs of SAD also consist of a yearning for carbs, and putting on weight throughout the winter season might have likewise assisted our ancestors to deal with the cold, the scientist states.