Is Seasonal Affective Disorder Hereditary?

Published: 03rd December 2008
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Seasonal affective disorder (SAD) is also known as "winter depression" or the "winter blues". This is a mood disorder that affects otherwise mentally healthy people in the autumn and winter months year after year. These people may start sleeping a lot more than normal, show signs of depression, be lethargic without reason and crave sweets and starchy foods, which will lead to weight gain. These symptoms will last throughout winter, but will start clearing up around spring when the sufferer will experience an increase in energy levels.

Seasonal Affective Disorder shows no discrimination and strikes regardless of race, class or occupation. It occurs in both the northern and southern hemispheres, and gets worse in countries that are further away from the equator and have a marked difference in the length of the day from summer to winter. While it affects both sexes, it is more common amongst women, and starts appearing between the ages of 24 and 40. It is, however, also found to affect some children and older people.

However, a lot of research has been conducted on this disorder, as reportedly 5% of the UK population suffers from it. This research has shown that SAD may be hereditary. Firstly, many people that suffer from SAD also have family members that suffer from this illness. Secondly, and more conclusively, a new study shows that this may be because of a genetic mutation that makes the eye of a SAD patient less sensitive to light. This means that people with this genetic mutation need brighter levels of light for them to function normally in the winter months. The gene that results in this disorder is called "melanopsin", which is a photo-pigment gene in the eye. This causes the disorder by making the eye less sensitive to light, thus increasing the need for more light during the winter months..

This photo-pigment gene has a type of protein that, while not involved in vision, is linked to many non-visual responses, such as the control of the sleep-wake cycle, the control of hormones and regulation of sleep. The mutation results in an aberration in the regulation of these responses, leading to the symptoms of SAD.

The study shows that while people diagnosed with this disorder do not necessarily carry the mutated gene; there is a strong link in the people who carry the gene and later get diagnosed with SAD. People with two copies of the gene are found to be five times more likely to present with SAD than people without the gene.

Thus, there is a very high probability that gene mutation is a major cause of SAD, but like all mental illnesses, it also has many other causes. Researchers say that further study is necessary before any conclusive statements can be made, and while lack of light may be a trigger for SAD, it is not the only explanation for this disorder. This research will also help scientists and doctors in devising better medication and treatments for people suffering from this disorder.

Rosana Horowitz is an expert in SAD and is familiar with its effects. She has tested many products that lay claim to being the market leader but she has found the Sunrise systems srs 250 clock to be highly effective in the treatment of SAD.

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