Light O'Clock

In this first episode of our new Interacting with Daylight mini-series, your host Caro is joined by Anna and Priji to discuss the Daylight Interaction Project, funded by the Daylight Academy. The project explores how people interact with daylight in everyday life and how this is shaped by factors such as location, built environments, culture and behaviours.

The episode focuses on the first part of their framework: Location. Through interview snippets recorded during the Daylight Academy Summer School in beautiful Chexbres, Switzerland, the hosts reflect on how geography, climate, temperature and landscape can influence experiences of daylight.

Interviewees come from diverse locations and latitudes: Singapore, Norway, Rochester (USA), and Costa Rica — offering perspectives on topics such as seasonal daylight changes, tropical versus northern light environments, and associations with sunlight and darkness.

Links and resources:

Anna and Priji’s publication describing their framework: https://doi.org/10.1038/s44271-024-00159-5

Visualisation of the framework’s “bubbles”: https://www.nature.com/articles/s44271-024-00159-5/figures/3

More about the Daylight Academy (DLA) Project: https://daylight.academy/projects/daylight-interactions/

Timestamps:

(00:00) Intro: the Daylight Interaction Project

(10:20) Project summary and interviewees

(13:51) Geolocation: latitudes, climatic zones, seasons, geographical context

(19:51) Snippets: associations with daylight and darkness

(30:50) Daylight as a placemaking tool

(34:21) Daylight vs sunlight

(37:55) Snippets: Seasonal changes and colours

(53:05) Reflections on seasonality

(59:33) Episode summary

(01:02:00) Outro: darkness associations

In this special episode of Light O’Clock, we share snippets from our very first live recording, captured on stage at Buch Wien in Vienna in November 2025.

Host Caro Guidolin and her colleague Marie-Luise Schreiter answer audience questions on chronotype, light exposure, sleep, shift work, and why people feel more tired in winter.

Many people notice changes in mood, energy, and motivation during the dark winter months. In this episode, we explore Seasonal Affective Disorder (SAD) and the broader experience of feeling low in winter and, importantly, what science-backed strategies can help.

We speak to Delainey Wescott about changes in sleep and circadian rhythms in SAD, and chat with Hester Parr and Hayden Lorimer about the Wintering Well project — an initiative that highlights the power of community, shared experiences, and collective coping during the darker months.

Throughout the episode, we discuss practical approaches to winter wellbeing, including light exposure, daily routines, cognitive reframing of winter, and small habits that can make a meaningful difference.

Links and resources:

Sleep in seasonal affective disorder: https://doi.org/10.1016/j.copsyc.2019.08.023

Retinal light sensitivity in summer and winter: https://doi.org/10.1016/j.jad.2021.04.084

Wintering Well resources (Living with SAD project): https://www.gla.ac.uk/research/az/livingwithsad/winteringwell/resources/. Includes: the guidebook Light is a Right: A Guide to Wintering Well, an online course developed by CBT experts, the Wintering Together Toolkit, and the SAD Stories Exhibition.

Timestamps:

(02:24) What is SAD and how is that different from the winter blues?

(05:16) Geography matters: who is affected by SAD?

(06:50) Circadian rhythms and sleep in SAD

(09:38) Light sensitivity in SAD

(11:50) Evidence-based strategies to alleviate SAD symptoms

(17:30) Summary

(18:35) The Living with SAD project

(22:30) Wintering Well Workshops

(25:45) My patch of winter sky, writing a letter to winter, and my kind of winter neighbourhood

(34:00) Winter Well resources created by the workshops

(36:28) The present and future of the Living with SAD project

(39:45) Wrap up and outro

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