Season 3 – Episode 4: Too early to think? Why school start times matter for sleep and learning

For our Season 3 finale of Light O’Clock, we dive into a timely and often overlooked issue: light pollution. Artificial light at night has become a constant in modern life — but what are the hidden consequences? Our guests, Barbara Harding, Travis Longcore and Karolina M. Zielińska-Dąbkowska, bring scientific insight into how nighttime light exposure may affect human health, including possible links to cancer, and how it disrupts wildlife, ecosystems, and natural rhythms. We also explore practical solutions: since we can’t simply switch off the lights, how can we use artificial light more responsibly to protect both ourselves and the environment? We explain the five principles for responsible outdoor lighting created by International DarkSky Association (now DarkSky International) and the Illuminating Engineering Society. Links and resources DarkSky International website: https://darksky.org/ Ecological light pollution: https://doi.org/10.1890/1540-9295(2004)002[0191:ELP]2.0.CO;2 Five principles for responsible outdoor lighting: https://darksky.org/resources/guides-and-how-tos/lighting-principles/ Outdoor artificial light and cardiometabolic risk: https://doi.org/10.1093/aje/kwae269 Artificial light at night and cancer risk: https://doi.org/10.1016/j.scitotenv.2024.177059 Timestamps (00:00) What is light pollution? (02:17) Light at night and circadian rhythms (05:18) Light at night and cancer risk (09:35) How light pollution is measured (16:11) What's the link between light at night exposure and disease risk? (19:00) Ecological light pollution (20:50) Effects of light pollution in animals: birds and turtles (26:00) Artificial light and animals' circadian rhythms (28:55) Light pollution changing predators-preys dynamics (32:30) Awareness towards light pollution in different countries (35:20) Why did we start to use artificial light in the first place? (40:30) What are the current lighting standards? (43:00) Different stakeholders involved in outdoor lighting (47:00) Five principles for responsible outdoor lighting (55:20) Wrap up and outro

Why do early mornings feel so brutal for teens? In this episode, we explore the science behind teenage sleep and circadian rhythms and why early school start times may be setting students up for failure. We talk to students from Italy and Germany, and sleep researcher Dr. Anna Magdalena Biller, to understand how biology, not laziness, is behind teen sleep struggles — and what schools, parents, and teachers could do about it. Big thanks to Margha, Lea, Giulia, Alice and Viola for sharing their perspectives on school start times! Links and resources related to the episode’s content: Review: Adolescent sleep & school timing Meta-analysis: School start times and academic achievement Flexible school start study (Germany) Expert report for Belgium (only in German) Timestamps (00:00) Intro & questions to teenagers (04:15) Circadian rhythms and sleep in adolescence (10:15) Consequences of sleep deprivation for teens (12:28) Initiatives aimed at delaying school start times (14:48) Studies on changing school start times (16:55) How do these studies measure sleep? (19:48) Is changing school start times beneficial for teens? (26:40) Challenges with implementation in schools (30:35) What other solutions can we use? (39:50) Outro

Today, more and more children around the world are developing myopia, or nearsightedness — especially in East Asia, where prevalence among school-aged children can reach up to 70%. Can simply spending more time outside in daylight help protect children from developing myopia? In this episode, our guest Asst. Prof. Raymond P. Najjar (National University of Singapore) breaks down: What we know about the link between light exposure and myopia in children Why kids aren’t spending enough time outdoors (and no — it’s not just because of tablets!) How we might be able to rethink indoor lighting in schools to better support healthy visual development Links and resources related to the episode’s content The influence of lifestyle and the environment on myopia: https://doi.org/10.1186/s40101-024-00354-7 Outdoor activity reduces the prevalence on myopia in children: 10.1016/j.ophtha.2007.12.019 Prompting parents to make their kids spend more time outdoor: https://jamanetwork.com/journals/jamapediatrics/fullarticle/2796425 More info on the LightSPAN project: https://eyenbrain.com/project-lightspan/ Timestamps (00:00) Intro and questions to kids (02:37) Guest introduction (03:30) Understanding myopia: causes and prevalence (06:58) The role of light and the environment (11:45) Challenges in increasing outdoor time in kids (16:27) Improving indoor lighting for myopia control: the LightSPAN project (23:09) Behavioural interventions with parents (27:14) Light exposure and myopia control in adults (29:30) Conclusions (31:07) Outro with more kids snippets

How does life in cities versus rural areas shape our circadian rhythms? How does access to electricity — or the lack of it — impact sleep timing? And what happens to our circadian rhythms when we move from an urban setting to camping outside? Our guest Luísa Klaus Pilz (Charité - Universitätsmedizin Berlin) comments on field studies carried out when she was a PhD student and postdoc at the Federal University of Rio Grande do Sul (Laboratório de Cronobiologia e Sono - HCPA/UFRGS). Links and resources related to the episode’s content https://www.nature.com/articles/s41598-018-29494-4 https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.773969/full https://www.cell.com/current-biology/fulltext/S0960-9822(16)31522-6 Timestamps (00:00) Intro (00:44) Questions from a Londoner (03:07) Guest introduction (03:57) Why care about rural vs urban light? (07:28) Sleep changes with urbanization (09:40) The effects of electricity and artificial light (10:49) Quilombola communities (16:38) Metabolic health differences (20:53) Rural occupations and light exposure (24:00) Other differences in behaviour (25:22) Adapting to a different environment (28:27) Future research questions (31:49) Outro For feedback and questions, you can contact us at: [email protected] Follow us on social media to stay up to date with our episodes and discover related content: Bluesky: https://bsky.app/profile/lightoclock.bsky.social Instagram: https://www.instagram.com/lightoclockpodcast/ Website: https://www.tscnlab.org/podcast

On 30 March 2025, Europe will switch to Daylight Saving Time (DST), moving clocks forward by one hour. While many people enjoy longer evenings, scientists in sleep and circadian research argue that DST can be harmful to our health. In this episode, we dive into the controversy surrounding DST and answer three key questions: Why do chronobiologists want to get rid of DST? What does the evidence say about DST’s impact on road traffic accidents? What does the public think about abolishing DST? We hear from experts, including Prof. Till Roenneberg, Prof. Sara Montagnese and Prof. Andrew Coogan, to break down the scientific and political debates around DST. Plus, we explore the short- and long-term health effects of DST on our health, the challenges of assessing this impact, and why public opinion seems to contradict expert recommendations when it comes to clock changes. Timestamps (02:11) DST and time zones (04:12) What happens to our clock when we change to DST (05:35) Short- and long-term consequences on DST (07:51) DST and social jet-lag (10:10) Challenges of studying DST effects on our heath (11:05) DST and driving performance (13:45) DST and road traffic accidents (17:37) Geography matters (20:30) What does the public think about clock changes? (23:15) Results of survey on public opinions in Ireland (26:20) Wording matters: Summer time/Winter time (30:24) Is this the battle chronobiologists should fight? (33:00) Summary and outro Follow us on social media to stay up to date with our episodes and discover related content: Bsky: https://bsky.app/profile/lightoclock.bsky.social Instagram: https://www.instagram.com/lightoclockpodcast/ Website: https://www.tscnlab.org/podcast

Light O’Clock is back with a brand new season! In the next five episodes, we’re looking beyond the biology of body clocks to explore how our modern world shapes our biological rhythms — and how politics and society influence decisions about our body clocks. We’ll cover the controversies around clock changes and school start times, discuss how indoor lifestyles might be affecting our vision, compare rhythms of people living in big cities and rural areas, and assess the impact of light pollution on human health and on the environment. Catch you on Tuesday, 25 March 2025! New episodes released every last Tuesday of the month. Follow us on social media to stay up to date with our episodes and discover related content: Bsky: https://bsky.app/profile/lightoclock.bsky.social Instagram: https://www.instagram.com/lightoclockpodcast/ Website: https://www.tscnlab.org/podcast

How do individuals with lived experience and researchers come together to co-design a scientific study? In this special episode of Light O’Clock, we hear from Patrica Pelosi and Nomhle Nhlapho, who have lived experience of bipolar disorder and have contributed to shaping the HELIOS-BD study (more in our previous episode). We also hear from Dr Amy Ferguson, who works closely with the Lived Experience Advisory Panel of the HELIOS-BD study and is the coordinator of the Circadian Mental Health Network. Links and resources related to the episode’s content:More on the Circadian Mental Health Network [https://www.circadianmentalhealth.org/] Have your say! Survey on what you think researchers should focus on when it comes to sleep, mental health and the body clock: [https://edinburgh.eu.qualtrics.com/jfe/form/SV_7P9EO2VGRjMQmAm] NOTE: This survey is only open to people living in the UK. How do you see light? AI-generated art depicting the inner experience of people living with bipolar disorder [https://www.heliosbd.com/gallery] Timestamps(00:00) Intro (00:55) Introducing the guests (04:36) What is the Circadian Mental Health Network? (12:45) What does co-design look like for the HELIOS-BD project? (19:00) Creative aspects of the co-design process (20:08) How collaboration helps lived experience individuals, scientists, and participants (23:14) Challenging aspects of co-design (32:10) Outro ContactFor feedback and questions, you can contact us at: [email protected] Follow us on social media to stay up to date with our episodes and discover related content: Instagram: https://www.instagram.com/lightoclockpodcast/ Website: https://www.tscnlab.org/podcast

On the occasion of Daylight Awareness Week 2024 (28-31 October) and Halloween, Light O’Clock is partnering up with the Daylight Academy to bring you an extra special episode that blends the science, the spooky, and the supernatural! Our host dives into the eerie mysteries of circadian rhythms, sleep and daylight with Prof. em. Anna Wirz-Justice, a pioneer in the field of chronobiology. Tune in to learn about the witching hour, twilight, the forbidden zone, sundowning and much more! This episode is supported by the Daylight Academy. Links and resources related to the episode’s content:Daylight Academy: https://daylight.academy/ Daylight Awareness Week 2024: https://daylight.academy/daylight-awareness-week-2024/ Timestamps(00:00) Intro (02:28) Circadian forbidden zone (06:33) Sleep deprivation symptoms (08:15) Sleep deprivation as therapy (11:30) Twilight (14:30) Dusk without electric light (16:13) Sundowning (17:03) Darkness (23:10) Lack of daylight in the North (27:23) The witching hour (29:07) Light therapy (33:22) Dark therapy (38:28) Outro ContactFor feedback and questions, you can contact us at: [email protected] Follow us on social media to stay up to date with our episodes and discover related content: Twitter/X: https://x.com/lightoclock Instagram: https://www.instagram.com/lightoclockpodcast/ Website: https://www.tscnlab.org/podcast

In today’s episode, we dive deep into the relationship between light, circadian rhythms and mental health with Prof. Daniel Smith from the University of Edinburgh. What role do light sensitivity and circadian rhythms play in bipolar disorder? How can we design studies to answer key questions in this area, and how can the involvement of patients ensure the success of a research study? Tune in to get the answers to these and many other questions about light, circadian rhythms and mental health. Links and resources related to the episode’s content:The HELIOS-BD study: https://www.heliosbd.com/ The AMBIENT-BD study: https://www.ambientbd.com/ Timestamps(00:00) Intro (01:25) Introducing Prof. Smith (02:45) Circadian rhythms and mental health (05:20) In which direction is the relationship? (07:25) The role of light (13:28) What is bipolar disorder? (16:45) Current treatment options (17:54) Bipolar disorder and light sensitivity (20:10) The HELIOS-BD study (29:08) Patient recruitment (30:58) The AMBIENT-BD study (33:40) Co-production of research studies (38:47) Outro ContactFor feedback and questions, you can contact us at: [email protected] Follow us on social media to stay up to date with our episodes and discover related content: Twitter/X: https://x.com/lightoclock Instagram: https://www.instagram.com/lightoclockpodcast/ Website: https://www.tscnlab.org/podcast

Did you know that your body has many body clocks? Like instruments in an orchestra, they each have a specific role to play, but how do they stay in rhythm with each other? In today’s episode, Dr. Laura Kervezee dives deep into the different body clocks, who is the conductor that makes our body run in harmony, and what happens when the rhythm goes out of sync. Timestamps(00:00) Intro (01:18) Introducing Dr. Kervezee (01:46) The different body clocks (03:20) How do these clocks sync? (05:00) The orchestra and the conductor (06:31) Clocks out of sync (09:18) Desynchrony in real life (10:25) Social jetlag (11:18) Health consequences (14:40) Future research: how to mitigate impact (17:30) What can you do as a shift worker? (22:25) Outro ContactFor feedback and questions, you can contact us at: [email protected] Follow us on social media to stay up to date with our episodes and discover related content: Twitter/X: https://x.com/lightoclock Instagram: https://www.instagram.com/lightoclockpodcast/ Website: https://www.tscnlab.org/podcast