Take your Health Seriously by Embracing the Dark
Article written by DarkSky NOVA Chapter Member Nicole Caplan, Environmental Science Duke University
As humans, each of us carries an internal clock that regulates our body’s perception of time. The steady melody of this clock’s chimes signifies when physiological processes are to occur, among which include sleep patterns, hormone production, digestion, and temperature regulation. These physical, mental, and behavioral changes that transpire over a 24-hour period are referred to as one’s circadian rhythm. Basic physiological processes that keep us alive rely on the synchronized rhythm of each person’s unique biological clock to function. Thus, a balanced circadian rhythm is essential for health and well-being.
The human circadian rhythm has been thrown into disarray because of an ever increasing amount of light pollution. Exposure to excess artificial lighting at night severely disrupts our natural cycle. A structure in the hypothalamus called the Suprachiasmatic Nucleus (SCN) is like the grandfather clock of the brain. The SCN decides when the pineal gland should secrete melatonin, a hormone that aids sleep. Normally, light exposure during the day prevents melatonin secretion so that we can stay awake, while darkness at night does the opposite so we can doze off and recharge.
However, overabundant lighting, specifically blue light, confuses the SCN’s directions. When our eyes make contact with blue light, photoreceptors in the retina send signals to the SCN that light is flooding the senses, which causes the suppression of melatonin. This becomes quite a problem, considering we need melatonin to sleep. Interference in this hormone’s production leads to a plethora of health problems.
Most intuitively, melatonin suppression leads to the onset of sleep disorders like insomnia. Other mental health concerns also come with a lack of sleep. Early research has shown that melatonin has anxiety-reducing effects. Reduced melatonin can thus interfere with sleep and worsen symptoms of depression and anxiety. On top of that, disruptions to the sleep-wake cycle increase the potential for obesity, early onset-diabetes, and certain cancers. Studies indicate that melatonin assists in activating lymphocytes, cells in the immune system that fight off cancer. This means that decreased melatonin levels increase cancer risk. One individual hormone can control so much.
The need to maintain a regulated circadian rhythm that allows for an adequate production of melatonin at night is clear. Unfortunately, light pollution makes this balance difficult to sustain. So, with a never ending expansion of artificial lighting, how can we protect our health? The most important goal is to be mindful of what light to use and at what times.
Warm-colored bulbs with a correlated color temperature (CCT) of 2200 K or lower are ideal for nighttime, while cool-colored lights are ideal during the day. Also, shielded fixtures that minimize glare are recommended for outdoor lighting and use of screens and indoor LED lighting should be restricted at night. Furthermore, we should abide by the Five Principles for Responsible Outdoor Lighting and use light only as needed.
All these guidelines can help ensure that the internal chronometers that reside in our brains tick with a thoughtful cadence; alert during the day and restful at night.
