Bright lights cause physiological changes in your body. Increased exposure to light affects the blood levels of the light-sensitive hormone melatonin, which at certain times of the day can be abnormally high. Also, the body has an internal clock that controls the daily rhythms of body temperature, hormone secretions, and sleep patterns. Bright light can delay or jump start this internal clock depending on when you are exposed to light. The prevalence of SAD appears to vary with latitude, age, and sex.
Younger women living at higher altitudes are at highest risk.
Treatment Discuss symptoms with your physician or a psychologist. Educate yourself on SAD and its treatment. Get as much natural light as possible during the fall and winter. Exercise daily, preferably outdoors, to take advantage of natural light. Work near a window, preferably a south-facing window.