Do you enjoy stepping outside at night and looking up to see a sky full of stars? For much of human history, that was the norm. But today, in many places, the night sky is drowned out by artificial light. While streetlights and glowing screens may seem harmless, they’re disrupting something vital—our circadian rhythms.
Circadian rhythms are the body’s internal 24-hour clock, regulating sleep, metabolism, mental health, and many other bodily processes. This system is primarily controlled by the presence or absence of light, signaling to our brain when it’s time to be alert or to rest. Natural sunlight in the morning wakes us up, while darkness triggers the release of melatonin, the hormone that helps us sleep. In our modern world, excessive artificial light—especially at night—is confusing our bodies, leading to circadian misalignment.
This phenomenon, known as light contamination, doesn’t just block our view of the stars—it affects our health. Exposure to bright, artificial light at night can suppress melatonin production, leading to sleep disorders, increased stress, and even a higher risk of conditions like obesity, heart disease, and depression. The glow from city lights, LED billboards, and our ever-present screens keeps our brains in a constant state of alertness, making quality sleep harder to achieve.
So what can we do? First, we can be mindful of our personal light exposure—using warmer, dimmer lights in the evening, reducing screen time before bed, and embracing natural light during the day. On a larger scale, communities can advocate for smarter lighting—such as shielded streetlights, motion sensors, and policies that reduce unnecessary nighttime illumination.
Light is powerful—it shapes our biology in ways we’re only beginning to understand. By addressing light contamination, we’re not just protecting our night skies—we’re protecting our health.
Keeping you in the dark,
The Western Slope Dark Sky Coalition