Nature at night
Why darkness is essential for so many animals, including humans
We came to the edge of the forest and the scent of damp earth poured out from the trees. In the dark, we could barely see the path in front of us, but we could smell the energy, the dynamism of this place on the air; roots and tubers buried deep in the soil, centuries of decay and regrowth, a sense of new life emerging from the old. We became lost in a labyrinth of shrub and thicket, and as we walked, our boots sank into the mud track, engulfing our ankles in a substance so thick that, without light, we slipped and toppled with each step.
Every few minutes, we heard the shriek of a barn owl from the canopy, and then a tawny owl echoing from the top of the hill. Between the two, we were half-mocked, half-motivated to keep climbing, until finally we emerged from the forest and out onto the peak of the hill. White moonlight shone down onto the haunted ridge of Kingley Vale and, in that small clearing, we stood surrounded by a cluster of yew trees, the source of so much mystery in this shadowy place.
Having lived in the South Downs almost all my life, I had
walked over this ridge countless times, but this was my first encounter after dark. By day, you could see the Sussex landscape yawning out towards the sea, but at night every tree and fence post became a shadow, made even more eerie by the local stories of slain Viking ghosts wandering the vale at dusk. What frightens us most about the darkness is also what draws us closer to it – the dangers and rewards of solitude, escaping the chaos of modernity as the rest of the world sleeps safely in their beds.
When we can no longer see who or what is lurking in the shadows, our imaginations conjure up new and unknowable forces. But this surge of fear can also make us feel more alive. Landscapes that were once familiar to us transform into unearthly spaces, and we are offered new territories to explore – as Lord Byron wrote in his poem Manfred, at night we can “learn the language of another world”. I decided to spend a year exploring the landscape after dark, travelling around the UK and the rest of Europe to see how our relationship with the nightscape has changed over time and across different
latitudes. In Arctic Norway, I experienced life without sunlight, as the polar night engulfs the city of Tromsø for three months of the year. In southern Finland, I swam wild under the midnight sun. I listened to cuckoos and nightjars at dusk, floated on the River Dart at sunset, and fed urban foxes in south London.
As I grew less fearful and more enchanted by nature after dark, I started to question whether our diurnal routines were more of a cultural norm than a biological one.
Since the earliest days of civilisation, we evolved to live our lives in daylight and hide away at night, and there are logical reasons for this. Our ancestors were preoccupied with survival – hunting, being hunted, gathering plants, building, socialising, farming and sleeping, all of which were entwined with the rhythms of day and night. In the early 1990s, at the National Institute of Mental Health in Maryland, Dr Thomas Wehr carried out an experiment in human photo periodicity (how the body reacts to day and night). By controlling the hours they were exposed to daylight, his team was trying to recreate prehistoric sleeping conditions in a group of young men.
While the conventional day length for the modern American measures 16 hours, the subjects’ days were shortened to just 10 hours. For one month, the men came to the laboratory each night to spend the remaining 14 hours in dark, windowless rooms, encouraged to relax and sleep as much as possible. In measuring their brainwaves, temperature and hormone levels, the researchers recorded a change in their nocturnal behaviour.
As the subjects adjusted to their new schedule, their sleeping patterns shifted into two distinct phases. While they only slept for an hour more than usual, the total sleep time was spread over a 12-hour period and split into two sessions. The ‘first sleep’ was a deep, slow-wave sleep, lasting around four to five hours before they awoke around midnight for an interval of quiet reflection and relaxed wakefulness, described by the researchers as a state of meditation. The subjects then returned to a ‘second sleep’, characterised by rapid eye movement and vivid dreams, before waking naturally after four to five hours.
Wehr guessed that this rhythm of sleep was much closer to that of our ancestors
When we venture outdoors after dark, we can experience nature up close, revealing the secret lives of wildlife with which we are not so familiar without sunlight.
who, like many other mammals, slept and woke in phases while never leaving the safety of their dens. During the meditative waking stage, the researchers also recorded an increase in prolactin, a compound associated with rest; high levels are usually found in nursing mothers and chickens brooding their eggs for long periods of time. The men also released higher levels of the growth hormones that help the body to repair itself, which reduced dramatically when the subjects returned to their normal schedules.
Written records show that the ‘first’ and ‘second’ sleep was still practised far into the early modern era, so what happened to cause us to fall out of this natural rhythm? A recent report by the Mental Health Foundation suggests that nearly a third of the UK population suffers from insomnia. One of the reasons for this is chronic exposure to blue light from our computer screens and phones. When our eyes are exposed to too much blue light at night, our bodies produce a lower amount
of melatonin, the hormone that regulates our sleep-wake circadian rhythms. Studies suggest that the combination of long working days, exposure to blue light, and failure to get enough sleep is disrupting our natural sleeping patterns, which means that, culturally, the night has become a time for much-needed rest rather than a chance to wake up and connect with our surroundings.
Humans are not the only species to have their circadian rhythms disrupted by artificial illumination. Light pollution has been proven to affect wildlife behaviour. Many animals, such as snakes, salamanders and frogs, restrict their movements when the moon is full, to avoid predators being able to spot them, meaning they tend to hunt more on moonless nights, But, as artificial light pollution spreads further across the habitats of these species, they’re spending less time hunting and more time waiting for the light to dim away – which it never does.
In cities, wild birds are shifting the start of their early morning dawn chorus to avoid light pollution from urban developments, though researchers suspect this could also be due to noise pollution. One study conducted at five airports in the UK found that birds had started to anticipate the morning rush of aircraft on the runway, changing their song times in order to avoid the noise and make themselves more audible to other birds. Since the dawn chorus usually takes place just before it is light enough for the birds to forage for food, by singing earlier, this means they are increasing their efforts without the opportunity to replenish their energy stores immediately afterwards. It also makes them more susceptible to nocturnal predators whose active hours are more likely to overlap with their own.
To combat increasing levels of light pollution, the International Dark-Sky Association was founded in 1988 to preserve and protect the night-time environment. In the UK, the Commission for Dark Skies is now the largest anti-light pollution campaigning group, and their work has contributed to the certification of several Dark Sky spaces, including
four International Dark Sky Reserves in the British Isles: the Brecon Beacons and Snowdonia National Parks in Wales, Exmoor and the South Downs.
Light pollution may not make the headlines as much as ocean plastic, rainforest deforestation or melting glaciers, but South Downs ranger Dan Oakley believes dark skies are just as important an issue for life on Earth. “Under a really dark sky like on the South Downs, we can see more than a thousand stars,” says Dan. “We can even see our own galaxy stretching across the sky. The Milky Way is our home and, without dark skies, we just can’t see it.”
In our anthropocentric world, to look up at the night sky reminds us of our place in the universe, that we are only one species in an ecosystem of billions. When we venture outdoors after dark, we can also look down at the world around us, to experience nature up close, revealing the secret lives of wildlife with which we are not so familiar without the help of sunlight.
A patch of British heathland, globally rarer than rainforest, is one of our most precious and fragile ecosystems, but many of its most enchanting species only reveal themselves after dark. On a warm summer night, nocturnal ramblers are rewarded with glow-worms shining in the grass like beacons, nightjars churring through the forest, bats searching for moths in the moonlight, and badgers, stoats and deer weaving like shadows through the thickets.
Western civilisation may be largely diurnal, but to spend time outdoors after nightfall is natural behaviour from which we can all benefit. A phone, flask of coffee and a friend is all we need to venture out into the dark wilderness, tuning into the sounds, smells and textures of the landscape. It’s a chance to break out of our comfort zones and liberate ourselves from the idea that the nightscape is a place for other creatures to enjoy without us.
WANT TO COMMENT? Should we spend more time outside, enjoying what the night has to offer? Email us at wildlifeletters@immediate.co.uk