Everyone says it: it's obvious that turning on the lights at night is a source of safety.
Everyone, that is, except the statistics!
Let's take a trip into the land of preconceived ideas and popular beliefs: what's really going on?
safety :
insecurity :
Doctoral Thesis: Chloé BEAUDET - INRAE 2025
Socio-economic analyses of light pollution reduction policies
Light pollution has increased significantly in recent decades and has negative impacts on biodiversity, nocturnal ecosystems, human health, astronomy, and energy consumption. Local authorities have several tools at their disposal to reduce this pollution, including turning off streetlights at night, reducing light intensity, or changing the color of lighting fixtures. However, public policies often focus on environmental benefits and do not sufficiently account for social dimensions such as residents’ acceptance and perceptions of safety1.
This thesis analyzes light pollution reduction policies implemented by French municipalities and their socio-economic consequences. It aims to integrate citizens’ preferences into the design of public lighting policies and to develop decision-making tools that reconcile ecological objectives with social expectations2.
1 Falchi et al. (2016). The new world atlas of artificial night sky brightness.
2 Beaudet C. (2025). Towards Sustainable Lighting: Socio-Economic Analyses of Light Pollution Reduction Policies.
3 Beaudet et al., Chapitre 1 – Social acceptability of public lighting changes.
4 Beaudet et al., Chapitre 2 – Mapping preferences from discrete choice experiments.
5 Beaudet et al., Chapitre 3 – Planning sustainable urban lighting.
6 Beaudet et al., Chapitre 4 – Identification of public lighting switch-off policies.
7 Beaudet et al., Chapitre 5 – Impact of lighting switch-off policies on crime.
It all starts in childhood, and is intrinsic to our evolution: from the age of 1, we begin to experience night terrors, which are unconscious and due to the establishment of biological rhythms. It's especially terrifying for parents, because the child won't remember it when he wakes up. The sleep phase is deep sleep.
Then, around age 2, the nightmares begin. These are in a conscious phase: “REM” sleep. That's why it's possible to remember them after waking up.
Since both phenomena occur during sleep, generally at night, the association “night = nightmare” becomes obvious. Adults speak of “night terrors”. The machine is up and running.
After this fine start, let's add children's stories and legends.
Games, fairy tales and legends all play their part.
It's a good time to let the imagination run wild. Often in connection with scary stories and crimes.
Let's remember an obvious but totally overlooked detail: human eyes are optimized for daylight vision. At night, in low light, they are very inefficient. Another sense then takes over: hearing.
We observe a phenomenon known as hyperacoustics. Unaccustomed to using our ears, the slightest noise is perceived as strange and alarming.
TV and cinema do nothing to help matters. The master of suspense, Alfred Hitchkock, made great use of dark scenes, in the dark and at night. Precisely to let the imagination do the work!
The film "noir" genre took off thanks to him.
In terms of culture and language, there are some interesting details. The Latin word “obscurus” means “towards the shadows”. This word has evolved in many ways. For example:
The two terms are etymologically close, and clearly show the association between the absence of light and fear and the unknown.
We're also familiar with the terms “black magic” or “black masses”, in reference to malicious practices against people. Again, in the collective unconscious, the association between darkness and danger is realized. It's a very ethnocentric and mostly false point of view.
And in those dark times, when black magic was at work, it was not until the Enlightenment century that knowledge advanced, and the unknown receded. We still see a name that uses the notion of darkness and light in a figurative sense, but one that remains ingrained in everyone's mind.
The link between the absence of light and action
Burglaries happen at night. I know someone who was asleep when the burglars broke into his house!
Well... no. It's one example, which will induce a feeling, but certainly not a statistic.
Let's talk statistics.
64% of violent thefts are committed during the day, 36% at night.
74% of non-violent thefts are committed during the day, 23% at night.
Studies show that the majority of burglaries take place during the day. The reason for this is simple: burglars generally act only when the house is empty.
source : Verisure
These are the times when you leave for work, when you pick up your children from school - in short, when you're away.
During the day, from 6am to 6pm: 87%, at night : 13%.
Source : French Ministry of the Interior
April 2026: french author Sébastien Bohler (Ph.D. in neurobiology) publishes a book titled Why Are We Afraid?
Some psychological experiments require nothing more than a little time and a good pair of shoes to carry out. Take a walk in the forest one day when the sun is shining brightly. Notice how carefree and relaxed you are, hands in your pockets, breathing in the air and whistling like a finch.
Then, a few hours later, return to the same forest after dark. A moonless night. Observe your reactions once more. Your heart rate? It’s sped up. Do you hear a noise? You freeze, your heart pounding. Does a breeze brush against your skin? You flinch, your muscles tense to the breaking point. What’s going on?
At Victoria State University in Australia, a team of neuroscientists and psychologists tested this phenomenon in their laboratory. To do so, they had volunteers undergo an MRI scan and measured their brain activity under two conditions. First, when the inside of the MRI scanner was illuminated by powerful LED lights, and second, when all the lights were turned off.
They then witnessed a strange sight. When the lights in the room are on, the amygdala is inactive. When the lights go out, however, the amygdala lights up. It’s like a Christmas light string on alternating mode!
In the dark, the amygdala triggers fear. Adrenaline and cortisol surge through the veins, putting the senses on high alert, accelerating the heart rate, and dilating the pupils. You may well be sitting in a state-of-the-art laboratory in the basement of a concrete building in a 21st-century megacity—a place where there are no snakes, no spiders, no vertiginous cliffs, and no risk of suffocation—but nothing helps: the amygdala plays its part, a script etched into the fabric of our emotions since time immemorial.
This ancestral reflex likely dates back to times before the mastery of fire—more than 600,000 years before our era. For a group of Paleolithic humans, nightfall was the moment of greatest danger.³⁴ It was the hour when predators prowled, when a leopard might pounce from the tall grass and snatch a child from its parents. The amygdala has retained the memory of that fateful moment.
When humans mastered fire, darkness receded. On the day a clan member first struck sparks from a flint, the amygdala was soothed by a bubble of light in the middle of the night. And the same phenomenon occurs again 600,000 years later, when a technician in an Australian laboratory flips a switch to turn on the ceiling light, causing the amygdala of his patients to go dark. An eternity has passed, yet the amygdala has not changed.
It is no surprise, then, that dawn is synonymous with hope in all human civilizations, and night a symbol of misfortune. Whether in sacred texts, folk tales, ancient epics, or founding myths, light still represents good, and darkness represents evil.
This is what is known as an anthropological invariant—a constant that depends neither on the era nor on where one lives. For regardless of where in the world they live, all humans possess an amygdala that has retained this original setting.
Since it is hardwired into our genes, the fear of the dark begins to develop in early childhood. For a toddler, fearing the dark is even more vital than it is for an adult. In the wild environment where our ancestors lived, an infant was particularly vulnerable when the clan was plunged into darkness. It was by curling up close to its parents or guardians that the infant could minimize the risk of being snatched by a predator.
The truth is actually far more ruthless than that and offers a concrete illustration of what is known as natural selection. A child who did not fear the dark would see their chances of survival greatly diminished. They would be effectively eliminated by natural selection. As a result, only young humans with an amygdala that detests darkness survived. And they have passed this fear down to all the children of the Earth.
Fear of the dark peaks around the ages of 4 to 5, usually persists until around age 10, and then gradually subsides as the child comes to understand their environment and reassures themselves through their increasingly developed ability to distinguish between imagination and reality.³⁵ But this primal fear sometimes persists into adulthood and can take the form of a phobia of the dark: nyctophobia. This condition is more widespread than one might think: according to some studies, half of young adults cite the fear of the dark among their top five fears
J. Levos, T. Lowery Zacchilli, « Nyctophobia : From Imagined to Realistic Fears of the Dark », Psi Chi-Journal of Psychological Research, vol. 20, n° 2, 2015.
Beyond its traffic benefits, visibility is a tool of social control, and the act of lighting the city a police measure that secures people and property at night.
It's undeniable that urban lighting plays a significant role in ensuring the safety of people, traffic and property in the city at night.
That it contributes to the feeling of safety among many users of night-time spaces, and thus enables greater investment in urban public spaces, is understandable.
However, the links between night and insecurity, light and safety, are not so simple and certainly not mechanical.
To illustrate the complexity of these links, I'll draw on feminist-inspired work that takes a gendered approach to this issue, revealing the sociosexual divisions that run through the nighttime space and place it in tension.
Let's not aim for exhaustiveness, but refer to the research of Stéphanie Condon, Marylène Lieber and Florence Maillochon, who remind us that the constraints imposed on women by the male monopoly of public spaces also have their temporal dimensions.
What I find particularly interesting here is that their analysis of the National Survey on Violence against Women in France underlines that “certain apprehensions remain out in the open”:
While a small majority of the women surveyed (between 45% and 55%) are not frightened by the idea of going out alone, a sizeable proportion do express concern about travelling, particularly at night.
For even more of them, going out alone at this time means choosing routes and neighborhoods to cross.
Clearly, it's at night that people are most afraid of going out, whatever the location.
And yet, certain spaces evoke dangers at any time of day: for example, almost one woman in five avoids going to a place where there is little traffic.
While a link between “the night” and women's spatial practices has been clearly established, the question of darkness does not seem to be so significant in the face of the effects of the social - and therefore constructed - dimension of the night:
It's night that evokes all the dangers, the time of day when a woman shouldn't be out alone.
If being in a poorly-lit place can be a source of anxiety, it is also suggested that there may be a time of day beyond which it is inadvisable - or frowned upon - to be out alone.
Hille Koskella has studied women's feelings of insecurity in the city of Helsinki, where summer nights are bright while winter days are dark and short.
It turns out that Finnish women make no difference in terms of danger between winter and summer nights.
So it's not the lack of light that keeps women on their toes, but the social dimension of the night.
And yet, the force of habit continues to make this safety issue one of the primary arguments put forward in favor of the deployment of public lighting.
Extract from “Samuel Chaléat – Sauver la nuit”, p121-122
