[Lee Yongbeom's Psychology of Happiness] Brain Waste Cleaning Time: Sleep Well Without Phone or TV for 'Good Sleep'

<20> The Best Tonic 'Sleep'

Iyongbeom Novelist

One traditional method of torture is to disrupt sleep. Depriving someone of sleep to break their will shows just how precious sleep is.

How long can a person endure without sleep? The official Guinness World Record is 11 days and 1 minute, set by an American high school student in 1964. However, Guinness soon discontinued this category due to health risks. The following year, a Finnish person set an unofficial record of 11 days and 12 hours. A British gardener established a record of 11 days and 2 hours in 2007. These records suggest that the human limit for staying awake is around 11 days.

◆ Why We Sleep = Spending about 33% of life in a vulnerable state sleeping is not only an energy waste but also increases the risk of being preyed upon. Yet animals must sleep to survive. The exact reason for sleep is not yet clearly understood, but several hypotheses exist in academia.

First, sleep evolved as a safety mechanism to protect life from nocturnal predators. In 1997, scientists released squirrels with disrupted biological clocks into the wild, and they were eaten by predators much earlier than normal squirrels.

To be safe during sleep, someone must keep watch. In 2017, a joint research team from the United States and Tanzania analyzed the sleep patterns of 33 African indigenous people over 20 days. The result showed that the time when everyone was asleep simultaneously was only 18 minutes. At least one person was awake during 99.8% of the sleeping time.

The survival chances of groups that kept sentinels while predators prowled would have been much higher. Therefore, humans evolved slightly different biological clocks by individual and age. We are all guardians of the group.

Second, sleep evolved to repair damaged brains or remove waste products. It was recently discovered that waste accumulated in the brain is cleaned during sleep. Other theories suggest sleep evolved for rest or to organize daytime memories.

◆ The Body’s Biological Clock = We have a biological clock that operates on a 24-hour cycle, called the circadian cycle. Even bacteria that appeared billions of years ago have a 24-hour biological clock. The 24-hour cycle arose due to the Earth's rotation causing day and night.

Humans, who depend on the sun, have three types of photoreceptor cells: rod cells that detect light intensity, cone cells that detect light color, and cells that sense biological rhythms based on light changes.

In the early 1990s, American psychiatrist Thomas Wehr asked people to live freely to study human sleep patterns. Initially, they slept 12 hours a day, but over time, sleep duration decreased to about 8 hours on average. Interestingly, they slept in two segments of about 4 hours each. This is a typical sleep pattern for mammals.

Why do we sleep in two segments? A 2015 analysis of sleep patterns among indigenous people in Africa and South America revealed that those living in traditional ways slept in two segments. This is because people living near the equator moved northward, where nights became longer. The length of the night on the winter solstice exceeds 14 hours, making continuous sleep difficult. The habit of segmented sleep disappeared as humans began to use fire to illuminate darkness and increased nighttime activities.

Normal sleep duration is 7 to 9 hours per day. However, with the development of artificial lighting and increased night work, modern people's sleep time is gradually decreasing. We sleep more than an hour less than the generation living 100 years ago. As a result, modern people experience unprecedented disruptions in their biological rhythms.

One factor affecting modern sleep patterns is "social jet lag." Social jet lag is mainly found in shift workers or those working overnight in service industries. It also occurs in people who go to bed late and wake up late or catch up on sleep during weekends.

As people age, they tend to go to bed earlier and wake up earlier, and they wake easily from minor stimuli. The reduction in sleep time after middle age is due to increased sensitivity to stress hormones. While stress hormones have little effect in youth, as people age, even slight increases in stress hormone levels cause many sleepless nights.

Sleep Time Reduced by 1 Hour Compared to 100 Years Ago Due to Lighting Development
Modern Night and Shift Work Disrupt Sleep Patterns
Sleep Deprivation Affects Depression, Memory, and Judgment
Women Working Night Shifts Over 6 Months Have 1.5 Times Higher Breast Cancer Risk
People Sleeping 4-5 Hours Have 4 Times Higher Traffic Accident Rate
To Sleep Well, Complete Isolation from External Stimuli Is Necessary

Chronic sleep deprivation destroys life. It affects judgment and reaction speed, depression and anxiety, immune function, cancer, neurodegenerative diseases, obesity and diabetes, cardiovascular diseases and strokes, concentration, and memory. Therefore, some experts argue that sleep has the most critical impact on survival. Sleep deprivation is a disaster for modern people.

Lack of sleep impairs cognitive ability as if one had consumed alcohol. The brain of a young person who has not slept for 36 hours resembles that of a person in their 60s. Becoming dull when sleep-deprived is because the brain perceives sleep deprivation as an emergency. When sleep is lacking, the brain supplies glucose to the heart and muscles and enters survival mode. When there is no room to care about anything beyond survival, we lose the capacity for rational judgment.

Women who work night shifts for more than six months have a 1.5 times higher risk of breast cancer. People who sleep less than six hours a day have higher early mortality rates. Those who sleep only 4 to 5 hours have about four times higher traffic accident rates. The likelihood of workplace accidents is also 2.7 times higher. Ultimately, lack of sleep can cost lives.

◆ How to Sleep Well = Sleep cycles between light and deep sleep in 90-minute intervals. If you sleep for 7 hours and 30 minutes, the cycle repeats five times. Once awakened, it is difficult to fall back asleep within 90 minutes no matter how hard you try. In such cases, it is better to do something else until you feel tired again rather than forcing sleep.

So, what are some ways to fall asleep quickly?

First, take a lukewarm shower before bed. Lower body temperature helps you fall asleep easily. Taking a lukewarm shower 1 to 2 hours before bedtime can lower body temperature. Warming your hands and feet is also effective. As your hands and feet warm, your body temperature drops. Conversely, an excessively warm sleeping environment disrupts sleep. Avoid strenuous labor or exercise before bed as they raise body temperature.

Second, be selective about food intake. Eating a lot before bedtime increases metabolism and raises body temperature. Late-night snacks are not only unhealthy but also interfere with sleep. Especially drinking alcohol with spicy snacks is the worst choice. Spicy food raises body temperature and causes frequent awakenings. It is well known that caffeine beverages disrupt sleep. Instead, drinking warm milk helps with sleep.

Third, avoid blue light from electronic devices. Visual cells that detect biological rhythms adjust the biological clock based on blue light from outside. At night, it is important to avoid blue light from smartphones, TVs, and computers. Instead of looking at your smartphone in bed, reading or listening to music is better.

Fourth, change sleep habits. Sleeping face down, watching horror movies, or eating stimulating foods can cause nightmares. Sleeping in a bed that gently rocks side to side is known to help you fall asleep faster and deeper.

On hot summer nights, the battle with sleep begins. Simply closing your eyes gently can rest your brain. However, resting while watching a cellphone or TV is ineffective. To sleep well, the brain must be completely isolated from external stimuli.

Novelist