Every year I approach the end of March and October with the same growing anxiety that my sleep patterns will be disrupted and I'll be tired, grumpy and generally miserable for the better part of a week. Setting the clocks back and forth an hour to save energy might have made sense in the early nineteen centuries, but now we know that very little energy is actually saved (Havranek T. et al, 2018). Aside from making me pretty unpleasant to be around, daylight saving time (DST) time changes have been shown to affect both our physical and mental health.

The most prominent study examining DST-related mental health effects found that the Fall time change (when we get an hour of sleep) was associated with an 11% increase in hospital admissions for depression in Denmark (Hansen BT. et al, 2017). There is also some limited evidence that the spring transition (when we lose an hour of sleep) is associated with increased suicide mortality rates (Lindenberger LM. et al, 2019). However, there is little evidence about the more general effects of transitions on mental well-being. Two studies to date have focused on self-reported life satisfaction, both of which reported a small decrease in life satisfaction following the Daylight Savings Time change (Kuehnle D. & Wunder C., 2014; Kountouris Y. & Remoundou K., 2014).

In a new study, Costa-Font and colleagues (2024) aimed to extend the work of these studies by:

• Hour-by-hour comparisons of differences in life satisfaction change in months close to differences around the last Sunday of the month (as a counterfactual).
• Examining broader outcomes to explore possible mechanisms underlying the reported mental health effects.
• Conducting a cost-benefit analysis for canceling DST time changes.

Research shows that the Spring Daylight Savings Time clock change is associated with a small decrease in life satisfaction.

Methods

The authors analyzed data from the German Socio-Economic Panel (SOEP) between 1984 and 2018. The study sample consisted of adults interviewed during the two weeks of the spring and fall time changes. They also interviewed participants on the last Sunday of the month fortnightly in the previous two months and the following two months (as a counterfactual). Participants were asked to rate how satisfied they were with their lives and dreams (0 = completely dissatisfied; 10 = completely satisfied). They were also asked how much they had felt time pressured or their mental health had affected their work/daily activities during the past four weeks.

The researchers used several approaches to address the research questions:

1. A design called regression intercept (RD) was applied to compare responses immediately before and after the Spring and Fall time changes.
2. A RD design combined with a differences-in-differences (RD-DiD) design was used to compare RD results with the mean difference in responses seen in counterfactual months.
3. Heterogeneity (variation) in effects was explored by stratification analyzes by sociodemographic subgroups such as male/female, full-time/part-time, with/without children, blue/white-collar worker, work hours, and low/high time stress.
4. Event-study analyzes were used to examine longer-term effects by comparing differences in responses on either side of the biweekly clock changes on either side of the last Sunday of the month in counterfactual months.
5. A cost-benefit analysis was conducted to stop DST time changes.

Participants were interviewed before and two weeks after the clock change and asked to rate how satisfied they were with their lives and their sleep.

Results

Both RD and RD-DiD analyzes showed A decrease in life satisfaction immediately after the spring transition. The RD analysis showed a 1.39% (-0.058 standard deviation (SD)) decrease in life satisfaction after the clock change, while the RDD-DiD analysis showed a 1.44% (-0.060 SD) decrease in life satisfaction compared to normal months. This negative effect on life satisfaction lasted for about six days.

The authors found that when examining potential mechanisms by which the clock shift may affect life satisfaction sleep satisfaction decreased (with a standard deviation (SD) of -0.213) and time pressure (the feeling of being rushed for time) increased (with 0.194 SD) after the spring time change. Analyzes stratified by sociodemographic subgroups showed that the negative effect of time change on life satisfaction occurred only among those who identified as male (-0.213 SD), not among women. Decreases in life satisfaction were also observed among people working full-time (-0.084 SD), blue-collar jobs (-0.358 SD), and those with high time stress (-0.083 SD).

Unlike the spring time change, researchers found that Life satisfaction increased after the autumn transition about 0.114 SD. This means that the Fall time change is associated with a 0.114 unit increase in the life satisfaction survey (0-10 scale) described above.

Theirs cost-benefit analysis The authors estimated that stopping clock changes (taking into account the costs of life satisfaction, health and productivity) would bring a per capita gain of €754.

Life satisfaction decreased after the Daylight Savings Time change as a result of decreased sleep quality and increased time pressure. The social cost of this reduction is estimated at €754 per capita income.

Results

This analysis of data from the German Socio-Economic Panel concluded that the Spring DST time change was associated with a small decrease in life satisfaction, mainly due to sleep loss and increased time pressure. This effect lasted for about 6 days and was mainly observed in men, full-time workers, blue-collar workers and those experiencing high levels of time stress. Abolishing DST in Germany would bring a net gain of €754 per person. The authors argue that welfare should be considered when evaluating DST policies.

Men, full-time workers and blue-collar workers experienced declines in life satisfaction.

Strengths and limitations

This study examines the broader effects of DST clock changes on general mental health, rather than the most serious effects recorded in people's medical records. The main advantage is that it used data over a 34-year period, which means it has a large sample size (>370,000 observations for life satisfaction), making its results more precise and sub-optimal to identify those most affected by clock changes. enables analyses. Additionally, in this regression intercept design, participants were randomly assigned to an interview before or after the clock change, based on the time of the clock change. This means that the two groups must have similar characteristics. It is therefore possible that the clock changes caused the observed differences in life satisfaction between the two groups (Moscoe E. et al, 2015).

Finally, the study aims to extend the existing literature by conducting a cost-benefit analysis, exploring the mechanisms by which transitions affect mental health, and including a counterfactual to demonstrate that differences in life satisfaction observed across hours differ. those seen in other months.

That said, there are several in this study restrictions we have to consider.

• First, it was the data that was analyzed self-reported by the participants themselves and therefore may be subject remember bias as a result of participants forgetting or lying. This can be a particular problem when exploring sensitive issues such as mental health, where there may be stigma associated with life satisfaction or poor sleep.
• Second, although the data from the German Socio-Economic Panel is broadly representative of the German population, if participation is related to how people perceive the time change, this may result in a biased estimate of the effects of the time changes.
• Finally, the study could not analyze life satisfaction before and after the clock change in the same people because participants only reported before or after the clock change (not both).

Implications for practice

This study contributes to the substantial current debate on daylight saving policies. Many countries, including Russia, Mexico, Brazil and Iran, have ended the practice in the last 15 years as a result of examining the negative consequences of transitions. most recently, The United States and the European Union are in the process of ending the clock change.

The cost-benefit analysis conducted by the authors provides a useful and unique evidence base for policy-makers concerned with the wider mental health effects of clock changes that are not recorded in daily health records. However, it is not clear whether the 1.4% decrease in life satisfaction after the Spring Time change is meaningful on a practical or clinical level. For example, would participants have noticed this change themselves (unless specifically asked about it), and is the difference large enough to adversely affect those at risk for certain mental health conditions? Future studies could use self-report data linked to people's medical records to investigate this.

The cost-benefit analysis conducted in this study provides a valuable evidence base for policy makers.

Statement of interest

There are no conflicts of interest to declare.

Connections

Primary paper

Costa-Font, J., Fleche, S. & Pagan, R. (2024). Welfare effects of time reallocation: Evidence from Daylight Saving Time. Economic91(362), 547-568.

Other references

Havranek, T., Herman, D. & Irsova, Z. (2018). Does saving daylight save electricity? A meta-analysis. Energy magazine39(2), 35-62.

Hansen, BT, Sønderskov, KM, Hageman, I., Dinesen, PT & Østergaard, SD (2017). Daylight saving time transitions and frequency of unipolar depressive episodes. Epidemiology, 28(3), 346-53.

Lindenberger, LM, Ackermann, H. & Parzeller, M. (2019). Controversy over daylight saving time (DST) – results of a 10-year (2006-2015) retrospective forensic autopsy study in Frankfurt/Main (Germany). International Journal of Legal Medicine133(4), 1259-65.

Kuehnle, D. & Wunder, C. (2014). Using a life satisfaction approach to evaluate daylight saving time transitions: Evidence from Britain and Germany. BGPE Discussion Paper, no. 156, Friedrich-Alexander University Erlangen-Nuremberg, Bavarian Graduate Program in Economics (BGPE), Nuremberg.

Moscoe, E., Bor, J. & Bärnighausen, T. (2015). Regression intercept designs are underutilized in medicine, epidemiology, and public health: a review of current and best practice. Journal of Clinical Epidemiology68(2), 132-43.

Photo credits