Over the next few weeks, we will be discussing the fourth in our series of the Vital Woman Code’s six stressors, light. We will look at how can light be considered a stressor, and how can it be detrimental to our health.
The rhythm of life is in harmonious balance with night and day, dark and light, the moon and sun. As too are our bodies. When this harmony is disrupted we start to see imbalances in the natural order of things.
The body clock
Many biological systems, particularly in humans, are determined by a 24-hour cycle called the circadian rhythm. This is also known as our internal body clock.
Responding to light and dark, the circadian rhythm regulates things like our sleep schedule, appetite, body temperature, blood pressure, cell regeneration and many other biological activities including our hormone levels.
Up until the twentieth century, the only light in the night sky was the moon and stars. As mankind has spread, so has electricity. Now the night sky is illuminated by towns, cities, and the roadways in-between.
Light pollution (or photo pollution) is not limited to big cities. It occurs anywhere that artificial light contributes to a loss of natural darkness.
The artificial sky glow caused by large cities can far outreach the city itself. An estimated 80% of people on earth live under light-polluted skies. As an example, for as far as 70km away, the glow from Las Vegas can be seen overhead. In Australia, the observatory at Coonabarabran is affected by the skyglow of Sydney 350km away.
Blue light exists naturally from the sun. It makes up a part of the electromagnetic spectrum we looked at previously. It is what makes the sky look blue. Natural blue light helps boost alertness, heightens reaction times, elevates mood, and increases the feeling of wellbeing.
Besides the natural sources, artificial blue light is emitted by digital screens such as TVs, computers, laptops, smartphones and tablets, as well as fluorescent and LED lighting. Modern electronic devices use LED back-light technology to help enhance screen brightness and clarity. As the use of technology increases, so does our exposure to blue light.
Our body clock relies on certain types of light exposure at certain times of the day. As we tend to spend more time indoors in classrooms, offices or at home, we spend more time exposed to artificial light sources.
Exposure to sunlight triggers the release of serotonin. This hormone is associated with boosting mood and helping a person feel calm and focused. Being in artificial light during the day, combined with reduced sun exposure causes a drop in serotonin, which can lead to depression.
Similarly, the release of melatonin, the sleep-promoting hormone, is triggered by darkness. Exposure to artificial lights at night and the blue light produced by electronic devices inhibits this release.
This disruption to both serotonin and melatonin production has many other far-reaching effects. Studies have shown a link between people with altered circadian rhythms such as shift workers and health conditions such as certain types of cancer, diabetes, heart disease, and obesity.
Next week, we will look more closely at how light pollution is damaging to our health, the health conditions directly related to it.