Project focus:
- Light pollution as an under‑recognized environmental and public health issue, with significant implications for sleep, circadian rhythms, chronic disease, and cancer risk.
What is light pollution?
- The disruption of natural light–dark cycles by excessive or poorly designed artificial lighting.
- Forms include:
- Skyglow: Upward-directed light scattered in the atmosphere, creating the familiar urban glow.
- Clutter: Excessive, tightly grouped bright lights that overwhelm visual processing.
- Glare: High‑contrast, uncomfortable brightness (e.g., full‑beam headlights).
- Light trespass: Unwanted light entering homes/rooms at night, disturbing sleep.
Global scale & trends:
- Using 2024 satellite data, Suhani showed that ~80% of the world lives under some level of light‑polluted sky.
- A study of 2011–2022 data suggests night skies are becoming ~10% brighter per year in many places.
- High levels of sky brightness cluster around densely populated and industrial areas, while truly dark skies are largely confined to remote, sparsely populated regions.
City-level investigation:
- Suhani built a DIY sky quality meter using Arduino and a light sensor.
- She mapped sky brightness across commercial, residential, and hospital zones in her city and found consistently high brightness in all these environments—areas where people live and sleep.
Health impacts & biology:
- WHO and the International Agency for Research on Cancer (IARC) classify night‑shift work—driven in part by chronic artificial light exposure—as a Group 2A “probable carcinogen.”
- Studies link light at night to increased risk of breast cancer (women) and prostate cancer (men).
Mechanism:
- Light reaching the eye signals from the retina to the hypothalamus and pineal gland, regulating production of:
- Melatonin (sleep hormone, peaks at night)
- Cortisol (alertness hormone, peaks in daytime)
- Blue‑rich light (common in LEDs, screens, “cool white” bulbs) mimics daylight and suppresses melatonin, delaying sleep and shifting the circadian rhythm.
- A cited Harvard study showed 6.5 hours of blue light exposure can delay the body clock by ~3 hours, contributing over time to:
- Chronic sleep deprivation and sleep disorders
- Cardiovascular issues
- Obesity and metabolic disorders
- Increased cancer risk
Special concern for adolescents:
- Adolescents already experience a natural ~1–2 hour circadian delay during puberty.
- Combined with evening/electronic light exposure and early school start times, this produces severe sleep deficits (often <6–7 hours instead of recommended 8–10 hours).
- Consequences: reduced concentration, memory and learning issues, slower reaction time, and long‑term risk of metabolic and cardiovascular disease.
Solutions and design changes:
- Replace old, unshielded streetlights with full cutoff, shielded fixtures that direct light only downward, as demonstrated in a NASA-documented before/after comparison in Los Angeles.
- Benefits include both reduced skyglow and better energy efficiency (less wasted upward light).
- Additional measures:
- Warmer-colored lighting (less blue content).
- Right-size illumination—no over‑lighting.
- Smart controls and motion sensors to dim or switch off lights when areas are vacant.
Starlight nonprofit & SkyQI initiative:
- Suhani founded Starlight, a nonprofit focused on:
- Raising awareness about light pollution and health.
- Running star‑gazing sessions and citizen‑science projects.
- Future policy advocacy around responsible lighting.
- SkyQI project:
- Participants upload night-sky photos from smartphones.
- An algorithm estimates sky brightness, assigns a Bortle scale rating (1–9), and plots locations on a global map.
- The site also hosts blogs, educational resources, and practical solutions.
- Starlight is actively seeking new members and contributors for outreach, tech, data analysis, and advocacy.
Closing reflection:
- Suhani urged participants to think not only about health risks but also about the loss of the night sky itself, pointing out that seeing only a handful of stars is not normal and inviting everyone to help “bring back the night sky.”