Seasonal affective disorder (SAD) is a form of depression that people experience at a particular time of year or during a particular season. Most of us are affected by the change in seasons – it is normal to feel more cheerful and energetic when the sun is shining and the days are longer, or to find that you eat more or sleep longer in winter. However, if you experience SAD, the change in seasons will have a much greater effect on your mood and energy levels, and lead to symptoms of depression that have a significant impact on your day-to-day life.
Most of the patients with SAD become depressed in the winter, at least in part because of a phase delay in circadiac rhythms relative to the sleep/wake cycle. Seasonal mood symptoms suggests that genetic aberrations may underlie the various abnormalities, which cause SAD symptoms are Feeling sad, grumpy, moody, or anxious, Lose interest in your usual activities, Eat more and crave carbohydrates, such as bread and pasta, Gain weight, Sleep more but still feel tired, Have trouble concentrating. the drug Melatonin secretion occurs later in the night.
The mean prevalence of SAD is two times higher. Over all prevalence studies, the correlation between prevalence and latitude was not significant. A significant positive correlation was found between prevalence and latitude there was a trend in the same direction were estimated at 18.8%