A Starless Sky

Disrupted Sleep and Circadian Rhythms

• Artificial light can disrupt the natural day-night cycle, which affects when animals sleep, wake, migrate, and reproduce.
• Birds that use moonlight to migrate may get lost and die.

Disorientation and Poor Navigation

• Light pollution can confuse animals' navigation, making it harder for them to find food, shelter, and mates.
• Sea turtle hatchlings may be drawn to bright lights from roads and houses instead of the ocean, where they need to go to survive.

Attraction to Artificial Lights

• Many insects are attracted to artificial light, which can lead to them being killed by light sources or becoming prey for predators.
• Billions of moths and other nocturnal insects are killed each year by artificial light.

Reduced Survival and Reproduction

• Light pollution can lead to reduced survival and reproduction in many species.
• By affecting the behavior of predators and prey, light pollution can alter food webs.

Impacts on Predation & Reproduction

• Light pollution can attract prey species to areas with artificial light, making them more vulnerable to predators.
• Disrupted circadian rhythms can negatively affect reproductive success by altering hormone cycles and timing of breeding activities.

Impacts on Plant Life

• Artificial light at night can trick plants into thinking it's daytime, causing them to bud and flower earlier in the spring, potentially leading to issues with
  frost damage and impacting the timing of pollination.
• Many nocturnal pollinators like moths and bats are disoriented by artificial light, leading to decreased pollination of night-blooming flowers and
  decreased seed dispersal.
• Continuous exposure to artificial light can cause stress on plant systems, impacting their photosynthetic efficiency and overall growth.

Impacts on Habitat Loss

• Some animals actively avoid illuminated areas, effectively excluding them from potential habitat.
• Nocturnal rodents such as some species of mice and shrews may avoid brightly lit areas, reducing their access to food and shelter.
• When animals avoid lit areas, it can effectively create barriers within their natural range, dividing their habitat into smaller, less viable sections.

Melatonin Disruption & Sleep Problems

• Exposure to artificial light at night, especially in the blue light spectrum, inhibits the body's natural production of melatonin, a hormone
  crucial for sleep regulation.
• Reduced melatonin levels due to light pollution can lead to difficulty falling asleep, disrupted sleep patterns, and reduced sleep quality.

Circadian Rhythm Disruption

• Light pollution disrupts the body's natural circadian rhythm, which is synchronized with day and night cycles, potentially impacting various
  bodily functions beyond sleep.
• A disrupted circadian rhythm can impact hormone regulation— increasing the risk of diseases— as well as mental health and metabolism,
  potentially leading to obesity.

Potential Health Concerns

• Studies have linked chronic light pollution exposure to potential health issues like increased risk of depression, obesity, diabetes, cardiovascular
  disease, reproductive problems and cancers.
• Moreover, numerous studies have linked working the night shift and exposure to light at night to increased risks for breast and prostate cancers
  and other health problems.