If colder weather and gloomy nights cause you to feel down, you’re not alone. This well-known phenomenon, called seasonal affective disorder, can explain why people feel low, irritable, and lethargic in winter. The condition could be debilitating and serious for many. Although SAD is a recognized type of clinical depression, experts are divided on what triggers the condition, with some even claiming it does not exist. But studies have found that your eye color may actually be one factor determining whether you are developing SAD. A survey conducted in 2014 found that about 8 percent of UK individuals self-reported changes with seasons that could be categorized as SAD.
Another 21 percent reported signs of subsyndromal SAD, which is a less severe form, often called winter blues. Although many individuals may suspect that they have SAD, the condition is usually diagnosed using the questionnaire for the seasonal pattern assessment. This asks individuals to answer a number of questions about changes in seasonal behavior, mood, and habit. The higher the questionnaire score for individuals, the more severe their SAD is. Nevertheless, these diagnostic tools may vary between organizations, which may occasionally lead to inconsistent diagnoses.
What actually causes SAD is still being debated. Some theories, such as the latitude theory, imply that SAD is triggered during the winter by decreased sun exposure. This suggests that SAD should be common in countries that are further away from the equator. Nevertheless, this theory has not been supported by a number of research studies.
Another theory indicates that SAD occurs when our circadian rhythm is interrupted as the days grow shorter. Other theories suggest it occurs with the body due to an imbalance in serotonin and melatonin. Serotonin makes us feel full of energy, while melatonin discharge makes us feel sleepy. Since serotonin is produced by melatonin, people with SAD may potentially produce too much melatonin throughout the winter months, leaving them in hibernation or down.
Each of these studies is inconsistent and, in several cases, contradictory. But because SAD is likely to be interconnected due to a combination of many biological and physiological factors working together, these different explanations for what triggers SAD might be interconnected.
SAD and your eye color-Research has uncovered evidence that a person’s eye color may have an immediate effect on how susceptible they are to SAD. A study used a sample of 175 students from two universities. Researchers found that in the seasonal pattern assessment survey, individuals with light or blue eyes scored significantly lower than those with dark or brown eyes
Below are some informational links about Seasonal Affective Disorder