Depression increases when clocks are rolled back, says Danish study; daylight saving time ends Sun.

On Sunday clocks will roll back an hour to end daylight saving time, which means the sun will rise later and set earlier by the clock, increasing the amount of darkness in most workdays. The time change leads to an increased rate of depression, says a study by researchers in the Department of Clinical Medicine at Aarhus University in Denmark, published in the journal Epidemiology.

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of highs and lows, unipolar sufferers remain low, often remaining apathetic, emotionally unresponsive and may become withdrawn, hopeless and overwhelmed.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)