It’s getting dark out again. Here’s why it’s actually good for your health.
As dark sky sanctuaries grow in popularity, scientists are revealing more of the benefits of darkness—from repairing DNA to improving your mental health.
On the first night of the new moon, I gaze at the sky from a campsite in Northern California. The night is so black that when I hold out my hand, I can’t see my fingertips. It’s not just an absence of light I’m experiencing: the darkness feels palpable, with a weight and texture of its own. I see the spinning pinwheel of the Milky Way overhead. The sight of this distant galaxy fills me with awe.
For most of us, it is a rare treat to see this hazy band of billions of stars. Light pollution now prevents more than one-third of the world’s population, including nearly 80 percent of North Americans, from seeing the Milky Way. And the presence of artificial lights at night is rising worldwide due to population growth and urbanization.
In our frenetic and bright world, more people like me are seeking out the quiet and profundity of lightless skies. “Dark sky sanctuaries” are becoming tourist destinations. People are trekking to places such as California’s Death Valley, New Zealand’s Tekapo Springs, and attending dark sky festivals to disconnect from light pollution and bask in the dark.
(Dark sky tourism is on the rise in the U.S. Here's where to go.)
As days grow shorter and daylight saving time ends in the U.S. on November 3, it’s time for us to embrace the approach of “dark season” in many parts of the globe. The changes may be jarring as we set our morning alarms an hour earlier and our workdays now begin in darkness. Yet, this seasonal shift, like dark sanctuaries, offers us much-needed respite from the glare of everyday life.
“Brightening our days and darkening our nights is critical to our health,” says Lynne Peeples, the author of The Inner Clock: Living in Sync with Our Circadian Rhythms. Finding a timely balance between light and dark helps us stay healthy.
Darkness and your health
Science has already revealed some of the harmful effects of light pollution—which is linked to insomnia, breast cancer, strokes, and fertility. A recent study even suggests it may contribute to the development of Alzheimer’s disease.
(Here's how light pollution is harming our health.)
But researchers are also starting to explore the opposite side of too much artificial light at night: they’re looking at the health benefits of spending time in natural darkness. We now know that basking in the dark can contribute to better health.
The most well-known of these benefits is the role darkness plays in prodding the pineal gland in our brains to begin releasing melatonin. This critical hormone doesn’t just help us sleep—it can reduce DNA damage by scavenging free-radicals, protecting against oxidative damage, and boosting the body’s own genetic repair machinery.
And that’s not all that darkness can do for you. A 2020 study showed that realigning the circadian clock with a compound that activates melatonin receptors in the brain can lower inflammatory markers, reduce anxiety, and alleviate depression.
The science of awe
Evidence is also mounting that the same alchemy that we feel in a dark sky sanctuary—a sense of wonder as we contemplate the vastness of the cosmos—is associated with better mental health and happiness.
It has long been clear that spending time in nature is good for your mental health—and a 2024 study published in the Journal of Environmental Psychology suggests that this benefits hold true at night as well as during the day.
(Nature really is good medicine. Science can explain why.)
“Experiencing natural darkness triggers a sense of awe and wonder in people which may be protective of human health,” says Ruskin Hartley, the executive director of Dark Sky International, a nonprofit group based in Tucson, Arizona, that has certified over 220 International Dark Sky places since 2001 and closely monitors the academic research on light pollution and darkness.
U.C. Berkeley professor Dacher Keltner captured this feeling in his 2023 book Awe: The New Science of Everyday Wonder and How It Can Transform Your Life. He argued that “awe is about our relation to the vast mysteries of life.” It is an emotion that has real biological implications: It can help lower the body’s inflammatory cytokine response—its response to attacking pathogens—as well as calm our nervous systems and trigger the release of oxytocin, a hormone that promotes positive feelings and is sometimes called the “love drug.”
The psychological benefits to spending time in the dark can be profound. Both mindfulness and creativity can be encouraged by darker spaces, as people who go to churches, synagogues, and mosques have discovered for millennia. There is a deeper reason why the lights go down before the curtains rise in theater productions and cinemas: darkness creates a liminal space where imaginations can flow more freely. The dimming light at dusk is nature’s own curtain fall.
How much darkness do you need?
My own fascination with the dark began in October of 2022, when I found myself floating in a Zodiac raft in the Arctic Sea. Our expedition guide had motored our rubber raft away from the artificial lights of our larger vessel, turned the outboard engine off, and instructed us to be silent. My shipmates and I looked up into the immensity of the celestial bowl as constellations spun in the black sky above. The darkness was so dense I couldn’t tell up from down, or where the night sky ended, and the inky sea began. I felt disoriented and elated.
I felt a surge of positive feelings flowing through me as I looked up at the stars on that dark Arctic night. The experience changed my relationship to darkness. As someone who’d always relished the idea of going to bed early to get a good night’s sleep, I decided to turn off artificial lights and electronic devices earlier in the evening. I also began wondering what “dose” of dark each night was ideal for my health.
Peeples, the author of The Inner Clock, told me that “Dimming the lights in the hours before bedtime—including electric screens—is critical for winding down, keeping our circadian clocks in sync, and encouraging our melatonin levels to rise. Once you climb into bed, full dark is best.” Her suggestion for those of us who don’t live in naturally dark areas? Sleep masks and thick blackout shades.
That’s more challenging, of course, for city dwellers where artificial skyglow invades nearly every public space. Peeples said the key is contrast: offsetting the bright day by creating a dark environment at night, especially during sleeping hours. For those who live in places with too much darkness: try sun lamps, which can be switched on and off to help realign circadian rhythms.
One of the biggest hurdles to embracing the dark may be the negative values we attach to it, including the belief that darkness is linked to disorder and crime (leading to more street lights in so many parts of the world) as well as to our deep-rooted fear of all things that go bump in the night.
Artists, poets, and songwriters have long understood our dread of the dark as well as the solace it can bring us. For me, it’s the Simon & Garfunkel hit song, "The Sound of Silence"—which starts off with the line “Hello darkness, my old friend”—that captures the essence of why escaping the light is necessary at times. It reminds us that some of our most profound moments of healing and insight happen in the dark.
