Researchers looked at data from the Danish Psychiatric Central Research Register from 1995 to 2012, looking at incident rates of unipolar depression. Unlike bipolar, which consists of cycles of highs and lows, unipolar sufferers remain low, often remaining apathetic, emotionally unresponsive and may become withdrawn, hopeless and overwhelmed.
Of 185,419 cases studied, researchers found that the end of daylight saving time in the fall was associated "with an 11 percent in the incidence rate of unipolar depressive episodes that dissipated over approximately 10 weeks." At the same time, "The transition from standard time to summer time was not associated with a parallel change in the incidence rate of unipolar depressive episodes."
Lead researcher Søren D. Østergaard said, "The transition to standard time is likely to be associated with a negative psychological effect as it very clearly marks the coming of a period of long, dark and cold days." (Read more)