How much light do we get exposed to after dark, and how does it matter?
People all over the world are living under the nighttime glow of artificial light, and it is causing big problems for humans, wildlife, and the environment.~ National Geographic
Sleep-wake cycles, or circadian rhythms, establish our biological clocks, allowing humans to react to the diurnal cycles. Circadian rhythms are universal patterns observed across bird, reptile, and mammal species.
The amount of light entering the eye is key in helping our brain distinguish times for wakefulness and times for sleep.
Circadian rhythm disruptions have also been observed in avian species, and light exposure was found to impact the genes governing internal clock regulation.
Similar outcomes have been discovered in humans as the distinction between day and night becomes more difficult to distinguish. We now have more devices than ever that emit various types of light. Our smartphones and laptops stream out blue light, while our indoor lamps and overhead lights flood our spaces with white light. There is increasing evidence that indoor light exposure, particularly at night, can contribute to circadian rhythm disorders that have long term health impacts.
The disappearance of our night skies has largely gone unnoticed as the increasingly urban-based population has never had the opportunity to view a pristine night sky.
The good news is that light pollution is reversible. City ordinances and active community efforts have made major impacts in reducing outdoor light pollution and preserving night skies.
There has also been increased advocacy to reduce circadian disruption from light infiltration via smartphones, computers, and indoor artificial light. Steps we can take to reduce our light pollution impacts include: switching light bulbs to warm-colored bulbs or LED lights, making active efforts to turn off unnecessary indoor or outdoor lighting, and protecting our eyes from blue light by using blue light glasses and screen protectors.~ “I Can’t Sleep… Can you turn off the lights?” – a Harvard article by Samantha Tracy
People living in cities with high levels of sky glow have a hard time seeing more than a handful of stars at night. Astronomers are particularly concerned with sky glow pollution as it reduces their ability to view celestial objects.
Is it Time to Get Up?
Artificial light can wreak havoc on natural body rhythms in both humans and animals. Nocturnal light interrupts sleep and confuses the circadian rhythm—the internal, twenty-four-hour clock that guides day and night activities and affects physiological processes in nearly all living organisms. One of these processes is the production of the hormone melatonin, which is released when it is dark and is inhibited when there is light present. An increased amount of light at night lowers melatonin production, which results in sleep deprivation, fatigue, headaches, stress, anxiety, and other health problems.~ National Geographic
The stark difference between the lights of an urban locality near a reserved forest.
What can we do about it as part of an individual lifestyle?
Any other suggestions welcome.