Over the last century, our experience of the night has radically changed. Hannah Dalgleish is investigating the consequences. She’s an interdisciplinary Research Fellow at the University of Southampton. At the 2026 British Science Festival, Hannah is delivering the Social Sciences Award Lecture: Southampton and the disappearing night.
In this guest blog for the British Science Association, Hannah discusses darkness, light and the inequalities that spring up between them, with writer and science communication trainer Alan Barker.
Southampton and the disappearing night
Date and time: 18 September 2026 - 19:00
Venue: Sir James Matthews Building - Lecture Theatre 1
Alan: You have a PhD in Astrophysics. Tell me a bit about the journey you’ve taken since then.
Hannah: I’ve always loved the night. And when I was studying astrophysics, I knew nothing about light pollution. Wasn’t interested. And then, later, I began to discover how we’re eradicating the night and filling it with light, and how this is creating so many different problems and inequalities. And I found myself journeying towards becoming a social scientist.
We’re beginning to value dark skies, aren’t we?
There are a couple of dark sky reserves in the region: Cranbourne Chase, the South Downs. But we need to be doing a lot more than protecting the places that are already relatively dark. Light pollution is growing by 10% a year on average – faster than any other pollutant – and cities make up a large part of that.
And what are the effects of too much light at night?
There are so many. We could start with inequalities around people working at night – the invisible workers who keep the country running, in hospitals, warehouses, often under harsh lighting environments. Precarious employment, very often, with negative effects on their health. Then we could talk about environmental effects: we think that introducing LEDs is environmentally friendly because it uses less energy, but it affects the health of all living things because it contains more blue light, which suppresses melatonin, a hormone secreted by the brain during the night that regulates the sleep cycle.
So an environmental effect creates a health effect
Yes. Things connect up. People in more affluent areas live in dimmer and cosier environments at night. But in less affluent areas – around the docks in Southampton, for instance, the lights look like blinding spaceships. But proving these effects of light pollution is very hard.
Academics only started thinking about these issues about 20 years ago, and so my research is trying to figure out how we can connect these topics up. I was awarded funding for a project called ‘Mapping the Night: encounters with liminal spaces’. We’re using Southampton city centre as a case study, and embedding a transdisciplinary approach to mapping the nighttime city.
Transdisciplinary?
The word can have different meanings. For this project, it means involving people from outside academic circles in research.
What does that mean in practice?
One of the things I’ve done is set up night walks, bringing together decision makers, council officers, police officers, ecologists, people from local industry – and guiding them on a walk to explore how they experience and perceive different nightscapes. I wanted to see the tension between what they expected and what they actually experienced.
And what did you discover?
For example, we have this feeling that the night is unsafe. But maybe, on the walk, you realise that this is just a preconception, based on the mood, or the lighting, or the absence of people. And then, one of the policemen started to learn about the effects of light pollution on bats, and he came off the walk really enthused about bats.
It sounds a very rich experience.
Yes, you’re embodying the experience of nighttime. I also did a walk on my own and recorded my experiences and reactions. Autoethnography! The night doesn’t frighten me. I’ve never once seen anything nefarious. Maybe I’m naïve. But most crime has fallen by 90% in the past 30 years and the UK is actually safer than ever. It’s also near-impossible to quantify the difference between daytime and nighttime crime because temporal data is not publicly available. The dearth of night-specific datasets makes research on the night incredibly difficult.
And linking hard data to lived experience is a challenge too.
Yes. In certain spiritual traditions, the night is very important for healing, for introspection, recovering from trauma. There’s hardly any research on this either. Meanwhile we’re eradicating the darkness and filling it with light – that’s primarily driven by capitalism and wanting more economic activity, so that we can work 24/7.
I’m thinking of the invention of fire…
Fire allowed us to stay awake at night, but it also created these focal points of safety where we told stories and built up our communities. Or found solace in the stars, the home of our ancestors. Now, we see lighting: electric lighting, cold, unfocussed, everywhere, disembodied. The shift from fire to LEDs has altered our culture, too.
What do you see as the output of this research?
This research is essentially exploratory. We’re gathering data – satellite data, socioeconomic data, qualitative data – and pointing out where we need more and better understanding. But I’m also keen to record our experiences of the night, and of how we’re degrading it. I want to show other researchers where they could take this work further.
We need a new discipline of night. No one discipline can cover it. The only way to do that is to bring together all these different perspectives, so that we can create something that transcends them. We’ve thought so little about our relationship with the night. How can we improve that relationship? How can we make the night better, healthier, something to be valued? That’s what I’d like the audience to be asking at the end of my lecture.
The 195th British Science Festival will be held in Southampton from 16 - 20 September 2026, organised by the British Science Association in partnership with the University of Southampton. All events are FREE and available to book at www.britishsciencefestival.org
Find details about all seven 2026 Award Lecturers here
Alan Barker is a writer and training consultant specialising in communication skills and science communication. Find out more about Alan’s work here
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