Seasonal affective disorder (SAD), also known as winter depression, winter blues, summer depression, summertime sadness, or seasonal depression, is a mood disorder subset in which people who has normal mental health throughout most of the year experience depressive symptoms in the winter or summer.
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, 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 9.8%