This blog post examines how light pollution and aging in modern society affect insomnia, exploring the causes and solutions.
According to a survey by the Korean Sleep Research Society, 22.8% of Korean adults suffer from nocturnal sleep disorders, namely insomnia. This indicates that a significant number of people experience discomfort in their daily lives due to insomnia, and the number of insomnia patients continues to rise. According to the Health Insurance Review and Assessment Service, the number of patients receiving treatment for insomnia is increasing significantly each year. The causes of insomnia are diverse, including stress, depression, pain disorders, age, and lifestyle habits. As insomnia is considered a representative modern disease, let’s examine its connection to light pollution and aging, two problems of modern society.
Sleep is a physiological state of unconsciousness that periodically restores the activity of the fatigued brain. Insomnia is a disorder where individuals struggle to enter or maintain sleep, even when given sufficient time to sleep. Entering normal sleep requires melatonin (often called the sleep hormone), a hormone that regulates the body’s circadian rhythm. However, patients suffering from insomnia due to light pollution experience inadequate melatonin secretion, leading to their condition. Melatonin is secreted by the pineal gland, an endocrine gland protruding from the dorsal surface of the diencephalon. The pineal gland detects light entering through the scalp, recognizing photoperiods such as night and day or seasonal changes in daylight hours. When activated, the pineal gland secretes melatonin to induce sleep.
In the morning, when exposed to sunlight, a pigment called melanopsin in the eyes absorbs light and activates the suprachiasmatic nucleus (SCN), an area near the pineal gland. The SCN consists of approximately 10,000 neurons. When activated, it directly inhibits the pineal gland, blocking melatonin secretion and preparing the body for activity. Conversely, as evening approaches and the amount of light entering the eyes decreases, the suprachiasmatic nucleus becomes inactive. The previously inhibited pineal gland then secretes melatonin, inducing sleep. This sleep-inducing melatonin is typically secreted most actively between 11 PM and 5 AM, enabling us to sleep well at night.
However, modern people often fail to get sufficient sunlight during the day and are exposed to artificial lighting, such as from electronic devices, at night. This is because most work is done on computers, and electronic devices like smartphones are used even outside of work hours. According to one survey, 54.4% of respondents reported that smartphone use reduced their leisure time, and 51.6% reported it reduced their sleep time.
Melatonin secretion can be suppressed even by faint light around 10 lux. Therefore, modern people exposed to the dim glow of electronic devices all day may have their melatonin-regulated biological clocks malfunctioning.
Beyond individual lifestyle habits, Korea’s severe light pollution is also problematic. Light pollution refers to excessive artificial lighting that keeps the night as bright as day. An international joint research team from Italy, Germany, the United States, and Israel analyzed satellite images of Earth and found that Korea has the second most severe light pollution among G20 nations.
Now, let’s explore the correlation between aging and insomnia. There’s a saying that as you get older, you lose your nighttime sleep. Indeed, according to a survey by the Korea Disease Control and Prevention Agency, 50% of the elderly suffer from insomnia. There are several reasons for this, but the primary one is the decline in organ function due to aging. Changes also occur in hormone-related metabolic processes, with the most significant being a decrease in melatonin secretion. Melatonin secretion peaks between ages 5 and 10, then declines after puberty. In the elderly, the overall amount of melatonin secreted decreases, leading to sleep difficulties. Additionally, the body’s circadian rhythm shifts earlier, causing melatonin secretion to end sooner and reducing sleep during the early morning hours.
Another cause is the various diseases that accompany aging. In old age, individuals often suffer from physical ailments affecting the cardiovascular, respiratory, and digestive systems, and the medications taken for these conditions can cause insomnia. Furthermore, chronic pain or itching caused by the disease itself often worsens at night, becoming a major factor disrupting sleep. Sleep apnea, common among the elderly, is also a cause of insomnia. As people age, the elasticity and tension of the muscles around the airway decrease, causing the airway to narrow easily during sleep. This makes breathing difficult, preventing deep sleep and leading to frequent awakenings.
Getting adequate sleep at the right time is essential for an energetic daily life. Suffering from insomnia leads to a foggy mind and heavy body, resulting in persistent daily fatigue. Therefore, both on an individual and societal level, insomnia should not be dismissed as a common ailment; appropriate countermeasures must be established.
Regarding light pollution, despite ranking second globally in severity, Korea’s efforts to address the actual problem remain inadequate. Unlike Australia or Canada, which began developing solutions in the 1990s, Korea only enacted its first legislation to reduce light pollution in 2013. Furthermore, citizens rarely report light pollution-related inconveniences to local governments. Consequently, even with existing light pollution laws, local governments have not enforced them and lacked the necessary detection equipment for enforcement. Recently, the video ACE system, capable of accurately measuring light pollution, was developed. Therefore, agencies responsible for light pollution enforcement must equip themselves with appropriate devices and actively pursue enforcement. Furthermore, drawing on examples from other countries, efforts should be made to raise citizens’ awareness of light pollution issues and encourage them to reduce it themselves. For instance, San Diego County provides guidelines that illustrate, through diagrams, how much unnecessary lighting can be reduced based on the height and angle of lights installed on building walls. It also specifically details the types of lighting fixtures effective for reducing light pollution.
While it is impossible to completely avoid physical changes associated with aging, such as decreased hormone secretion, frequent illness, and weakened muscle elasticity, maintaining one’s biological age through health management is crucial. Aerobic exercise and strength training increase deficient growth hormone levels. Since growth hormone is involved in enhancing skin and muscle elasticity and boosting immunity, consistently performing these exercises is beneficial.
