Light O’Clock is going live from Vienna at Buch Wien 2025 on Saturday, 15 November – and this time, you set the agenda for the episode!

Together with Marie Luise Schreiter, we’ll be diving into your questions about how light shapes our brains, bodies, health, and daily rhythms – live on stage.

What have you always wanted to know about light, sleep, or circadian rhythms?

Send us your question through this link: https://form.jotform.com/252533837926365

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