In this episode, I talk with Dr Bertel Teilfeldt Hansen of the Department of Political Science at Copenhagen University in Denmark. We talk about his involvement in this project looking at the impact of clock changes in winter-time on the incidence in depression, and how he got involved in the research.
The abstract for the paper can be found here.
Daylight savings time transitions affect approximately 1.6 billion people worldwide. Prior studies have documented associations between daylight savings time transitions and adverse health outcomes, but it remains unknown whether they also cause an increase in the incidence rate of depressive episodes. This seems likely because daylight savings time transitions affect circadian rhythms, which are implicated in the etiology of depressive disorder. Therefore, we investigated the effects of daylight savings time transitions on the incidence rate of unipolar depressive episodes. Using time series intervention analysis of nationwide data from the Danish Psychiatric Central Research Register from 1995 to 2012 we compared the observed trend in the incidence rate of hospital contacts for unipolar depressive episodes after the transitions to and from summer time to the predicted trend in the incidence rate. The analyses were based on 185.419 hospital contacts for unipolar depression and showed that the transition from summer time to standard time were associated with an 11% increase (95% CI: 7%, 15%) in the incidence rate of unipolar depressive episodes that dissipated over approximately 10 weeks. The transition from standard time to summer time was not associated with a parallel change in the incidence rate of unipolar depressive episodes. This study shows that the transition from summer time to standard time was associated with an increase in the incidence rate of unipolar depressive episodes. Distress associated with the sudden advancement of sunset, marking the coming of a long period of short days, may explain this finding.
In addition, Dr Hansen sent along the following text after the interview, to clarify part of our conversation:
“The researchers find that fatal traffic accidents in the US increase significantly on the Monday immediately after the change to DST in the spring and also on the Sunday of the change to standard time in the fall. They tie both to sleep deprivation.”
I hope you find our conversation interesting and thought-provoking.