The great time debate: What does the science say about daylight saving time (DST) and our health?

Aiste Steponenaite
2 hours ago
2 min read

Welcome to the first blog in our Early Career Researcher (ECR) Research Spotlight! With many of us changing our clocks at the end of October, this blog comes at the perfect time.

Dr Aiste Steponenaite is a Lecturer at University of Kent, specialising in circadian neuroscience, sleep health, and ageing. Her research explores how ageing and circadian disruption affect brain health, behaviour, and wellbeing, using both preclinical and human-centred approaches to inform real-world interventions.

She is particularly passionate about developing personalised, non-pharmacological strategies to improve sleep and circadian health, and she is involved in projects applying AI and machine learning to circadian and health data.

The clocks are changing soon. This October, millions in the UK and globally will experience the "fall back," when we gain an hour of sleep. But twice a year, Daylight Saving Time (DST) transitions force an abrupt misalignment between our internal body clocks (our circadian rhythm) and the social clock. Currently practiced in 71 countries, this biannual shift is a topic of intense debate for policymakers, public health experts, and, crucially, circadian scientists.

As a sleep and circadian neuroscientist, I am fascinated by the real-world impact of this shift on our health. To cut through the noise, together with our expert international team we conducted a global systematic review of over 20,000 research articles. We evaluated the impact of DST on critical public health outcomes, including heart attacks (myocardial infarction), traffic accidents, and sleep duration.

After identifying 157 relevant studies, the evidence was complex and often contradictory. However, a few findings stood out: the “spring forward” transition was associated with increase in myocardial infarction (heart attacks) in certain populations, but a decrease in crimes causing physical harm. There was also evidence positive effects during the autumn “fall back” transitions in reduced traffic accidents or all cause mortality, with some negative effects too, such as increase in crimes causing physical harm.

For many other measures, such as depression, sleep or cognitive outcomes the evidence was conflicting or weak. Our work, currently under review (and available as a preprint: A Systematic Review of Epidemiological Studies into Daylight-Saving Time & Health Identifying Beneficial & Adverse Effects | medRxiv), highlights an urgent need for more consistent and rigorous research to inform the public health policy discussion surrounding the clock change. Simply put, this topic is incredibly complex, and the evidence is far from uniform.

How the Circadian Mental Health Network supported my research

I was honoured and incredibly grateful to receive the Circadian Mental Health Network (CMHN) ECR Travel Award to present this work at the network's conference in Edinburgh in June 2025. It was a fantastic opportunity to engage with fellow researchers and establish fruitful collaborations.

Beyond the conference, the CMHN played a direct role in elevating this research to a wider audience. My presentation was noticed by the BioClocks UK team, which led to an invitation to be featured on the popular science podcast, Science Vs, to discuss the impact of DST on our health, as well as the fundamental importance of circadian rhythms for our wellbeing.

Blog by Aiste Steponenaite