In a few weeks, the clocks will be changed and daylight-saving time will begin. While the annual “Spring forward” of the clock means an hour less of sleep, the benefits of more daylight hours cannot be denied. Daylight-saving time was initially begun to give people more sunlight hours after work and eventually it was credited with saving energy costs as well. The opposite happens in the fall however, when clocks are turned backwards. Both time changes have been associated with various health issues, sleep disturbances and other adjustment issues, but new research shows that turning the clocks back in autumn, could trigger depression.
A study recently published in the journal Epidemiology looked at the number of people diagnosed with depression at psychiatric hospitals in Denmark. Analyzing a lot of data, the study showed increases in depressive episodes immediately after the transition from daylight-saving time to standard time. It started quickly too. In the study, diagnoses of depression rose 8% in the first month following the change. The study data and analysis was generated through the use of 185,419 depression cases registered in The Central Psychiatric Research Register in Denmark between 1995 and 2012. Researchers do not believe that the increase can be a coincidence since the timing and amount of cases is glaring.
Associate Professor Søren D. Østergaard from Aarhus University Hospital in Risskov, which is part of The Department of Clinical Medicine at Aarhus University was one of the lead researchers on the study. He stated, "We are relatively certain that it is the transition from daylight saving time to standard time that causes the increase in the number of depression diagnoses and not, for example, the change in the length of the day or bad weather. In fact, we take these phenomena into account in our analyses.” The team in Denmark collaborated with the psychiatry and political science departments at both the University of Copenhagen and Stanford University. The data was taken from patients who mostly had pretty severe forms of depression, but the authors of the study believe that cases of milder depression are also related to the change.
When the time changes in the fall, there is more daylight at an earlier time in the day, around 7-8am. Many people are still at home getting ready for work, or commuting to work at this time, whereas in the afternoon during daylight-saving time, it can get dark as early as 4pm in some areas, a time when many are still working. Coming out to a dark world every day after work can be a depression trigger for some.
Part of the rise in cases might also be due to the knowledge most patients have that the darker afternoons signal the coming of winter and a long period of darkness. Seasonal Affective Disorder (SAD) is common as well at this time of year, and some people start to feel worse emotionally as the daylight decreases. Suggestions to offset the winter blues include using a special sunlamp to catch some rays indoors, adjusting schedules and going outdoors whenever possible to take advantage of daylight hours. Keeping more lighting on in the house is another way to cope. For more information on the time change and what the study could mean for those who may have a tendency towards seasonal depression, take a look at the video below.
Sources: Aarhus University CNN Epidemiology