Many seasonal affective disorder suffers might wonder why they are affected by this disorder.  It is important to understand what this disorder is and why it affects so many people, because if you have SAD you will most likely develop depression like symptoms every winter season.  Although many people do develop this condition, some are more at risk than others for being diagnosed with SAD. It depends a lot on your sex, geographic location and genetics.
According to research, more females are diagnosed with SAD than males.  This does not mean that men do not get SAD it simply means that development of SAD is more rare in men.  However, if a male does develop SAD, studies indicate that their symptoms will be worse.
Where you live influences how likely you are to develop SAD because development of the disease depends on sunlight and weather.  SAD appears to be more common among people who live far north or south of the equator, think states that usually have snow during the winter months. This may be due to decreased sunlight during the winter, and the longer days of summer.
All mental illnesses usually involve some sort of family history.  As with other types of depression, studies do show that if SAD runs in the family, than you are more likely to develop the disease than someone who does not have relatives with the condition.