Light pollution is something we encounter in large cities, oversaturation of light especially in the late hours of the day is something we could try to control.
Some of the light that discourages sleep and promotes stress comes from sources we control, other sources of light are out of our reach. The screens in our hands are very different from the bright lights we’re subjected to when traveling.
In any case, in order to understand the harm to our health from light sources we need to look into circadian rhythms.
Circadian rhythm
Circadian rhythm is a biological process that regulates the physiological and behavioral changes in an organism over a 24-hour cycle, responding primarily to light and darkness in an organism’s environment.
There are four main stages in the circadian rhythm during a 24-hour cycle:
- Alertness and peak performance
- Drowsiness
- Deep sleep
- Dreaming (REM sleep).
The last stage, arguably the most important is most likely to be disrupted is sleep, especially in people with sleep disorders, shift work, and jet lag.
The interaction of hormones during a 24-hour cycle plays a crucial role in regulating the circadian rhythm. Hormones such as cortisol, melatonin, and adrenaline have peak levels at different times of the day, influencing the regulation of sleep, wakefulness, and overall physiological functions. For example, cortisol levels are highest in the morning, helping with alertness and wakefulness, while melatonin levels are highest at night, promoting sleepiness and helping regulate the sleep-wake cycle.
Light pollution
Light pollution refers to excessive and disruptive artificial light that affects the natural environment. This can have several effects on human health, including:
- Stress: Bright lights at night can disrupt the body’s circadian rhythm, leading to increased stress hormones such as cortisol.
- Sleep: Exposure to bright lights at night can interfere with the release of the sleep hormone melatonin, making it difficult to fall asleep and leading to poor sleep quality.
- Metabolism: Disruptions to the body’s circadian rhythm can also interfere with the regulation of hormones that control appetite and metabolism, leading to weight gain and metabolic problems.
- Cognitive function: Poor sleep and increased stress levels can impair cognitive function, leading to decreased attention and memory.
- Eye strain: Bright lights can also cause eye strain, leading to headaches and fatigue.
Light pollution can also have ecological impacts, such as disorienting and altering the behavior of nocturnal animals, and disrupting migration patterns and food webs.