Seasonal Affective Disorder (SAD)

Seasonal affective disorder (SAD), characterized by the onset of depression during winter months with less natural sunlight, is often accompanied by social withdrawal, increased sleep, and weight gain. Symptoms may start out mild and become more severe as the season progresses. It generally lifts during spring and summer and predictably returns every winter. People with BD can suffer from SAD, which needs to be treated to keep mood and motivation steady throughout the year. Causes are not known, but factors such as disrupted circadian rhythms and drops in serotonin and melatonin levels may trigger BD depression.