Daylight saving transition could increase depression

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(CNN) -- The extra hour of sleep you gain during winter may not outweigh the effects of the extra hour of darkness, according to a new study.

Depression cases at psychiatric hospitals in Denmark increased immediately after the transition from daylight saving time, the study found. An analysis of 185,419 severe depression diagnoses from 1995 to 2012 showed an 11 percent increase during this time period.

The cases dissipated gradually after ten weeks.

Researchers from the departments of psychiatry and political science at the universities of Aarhus, Copenhagen and Stanford were all aware of the negative effects associated with daylight saving time, such as the increased heart attacks and stroke risk.

They wanted to see what was true of standard time, especially because the time affects people around the world and can disrupt their circadian rhythms.

"The results should give rise to increased awareness of depression in the weeks following the transition to standard time," said Dr. Søren D. Østergaard, one of five study authors and associate professor at Aarhus University. "This is especially true for people that are prone to develop depression, as well of their relatives, who may be the first ones to notice the depressive symptoms."