Approved Research

Estimating the Effects of Daylight Saving Clock Changes on Cardiovascular Outcomes and Depressive Symptoms in the UK Biobank

Lay summary

Aims:

The main aim of this research is to estimate the effects of DST clock changes on incidents of cardiovascular disease and depression in the UK. Within this we will explore the effect of the clock changes on sleep, as well as the effect of sleep on cardiovascular disease and depressive symptoms. We will also examine whether the clock changes are associated with any other characteristics in UK Biobank participants.

Scientific rationale:

Daylight saving time (DST) is the practice of moving clocks one hour forward in the spring and one hour back in the autumn. It was introduced during World War 1 as a way of reducing energy use. DST is now in operation in 70 countries, including the UK, and affects a quarter of the world's population. However, there is growing evidence that DST clock changes may have adverse effects on population health. This is likely to be due to sleep deprivation and circadian disruption. Studies conducted outside the UK have reported increased incidence of heart attacks, strokes and depressive episodes in the weeks after the clock changes. This research has prompted countries to reconsider their use of DST and the EU voted to end its use after 2021. However, as the UK has now left the EU it is unclear whether DST will be abolished in the UK.

Project Duration:

The project will take 3 years.

Public Health Impact:

The evidence will then be used to formulate policy recommendations as to whether the UK should abolish DST clock changes. More widely, the research will improve our understanding of how sleep and circadian rhythms affect physical and mental health.

Current scope:

The primary aim of this project is to estimate the effects of daylight saving time (DST) clock changes on cardiovascular and depression phenotypes in the UK population.

More specifically it aims to:

1. Use regression discontinuity analysis to compare sleep phenotypes (self-reported and accelerometer data) before and after DST clock changes in order to estimate the effects of the clock changes on sleep phenotypes.
2. Conduct a phenome-wide association study (PheWAS) to identify other phenotypes associated with DST clock changes.
3. Perform Mendelian randomization (MR) analyses, using genetic variants identified by UK Biobank genome-wide association studies (GWAS) as being associated with specific sleep phenotypes (e.g. sleep duration, chronotype, insomnia etc.), to investigate the effects of sleep on cardiovascular and depression phenotypes.
4. Conduct within-family Mendelian randomization to assess the robustness of the results against population and family-level biases.

New scope:

5. Use regression discontinuity analysis to compare primary care-recorded sleep phenotypes before and after DST clock changes in order to estimate the effects of the clock changes on sleep phenotypes.

6.     Compare self-reported insomnia in UK Biobank to insomnia recorded in linked primary care records in order to establish whether they are measuring the same thing and picking up a consistent phenotype.