[Harumanbo Harucheonja] "As Sleep Debt Increases, Risks of Obesity, Diabetes, and Dementia Rise"

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"You need to let go of the 'illusion of knowing well' about sleep. And it is necessary to face your own sleep habits and conditions correctly."

Professor Jeong Ki-young, a neurologist at Seoul National University Hospital, said this based on his 25 years of experience as a sleep medicine specialist treating various patients. Professor Jeong was selected as a fellow of the prestigious American Academy of Sleep Medicine this year and also serves as the president of the Korean Sleep Research Society. To correct misunderstandings about sleep and raise awareness of its importance, he published . He emphasized, "Sleep is an important part of life, but the perception of sleep among Koreans remains stuck in the past," adding, "For perceptions about sleep to change, society must take the lead."

Various statistics also show that Koreans suffer from insufficient sleep. According to 2016 data from the Organisation for Economic Co-operation and Development (OECD), the average sleep duration of Koreans was 7 hours and 51 minutes, 31 minutes less than the OECD member countries' average of 8 hours and 22 minutes, ranking lowest. On World Sleep Day (March 17) this year, the global sleep solutions brand ResMed surveyed over 20,000 people across 12 countries, finding that Koreans' average sleep time was 6.9 hours, lower than the 12-country average of 7.16 hours. Satisfaction with the quantity and quality of sleep was reported as "dissatisfied" by 50% and 55%, respectively, higher than the 35% and 37% dissatisfaction rates for sleep quantity and quality across the 12 countries. As Professor Jeong puts it, Koreans live with a "sleep debt." This debt is a challenge that must be repaid not only individually but also nationally.

Professor Jeong Gi-young of the Department of Neurology at Seoul National University Hospital is explaining the "Power of Sleep" at Seoul National University Hospital in Jongno-gu. Photo by Hyesun Lim lhsro@

Professor Jeong said, "Just as the United States has declared sleep problems as a public health issue akin to epidemics or pollution, sleep is a societal issue beyond an individual one," pointing out, "Considering that Korea has the highest suicide rate in the world, the quality of sleep among Koreans is at its lowest." People tend to underestimate sleep problems, judging that losing a few hours of sleep won't seriously affect their health. However, even one night of poor sleep significantly impacts both body and mind. Professor Jeong explained, "In the short term, stress responses increase, and blood pressure and blood sugar levels rise," adding, "Emotionally, people become easily irritable, and anxiety and depression increase." In the long term, he noted, "The risks of obesity, metabolic syndrome, hypertension, diabetes, heart disease, and stroke increase."

Lack of sleep also affects dementia. Professor Jeong said, "Sleep helps remove amyloid, a toxic protein that accumulates in the brain, earning it the nickname 'the brain's janitor,'" adding, "If sleep disorders exist, the excretion of amyloid protein decreases, leading to increased accumulation in the brain and raising the risk of dementia." He continued, "A study in the UK on the relationship between sleep duration and dementia found that people in their 50s and 60s who slept less than 6 hours had a 20-30% higher incidence of dementia compared to those who slept 7 hours." There is also research showing that people who sleep 5 hours have twice the risk of cardiovascular disease compared to those who sleep 7 hours.

Professor Jeong Gi-young of the Department of Neurology at Seoul National University Hospital is explaining about the "Power of Sleep" at Seoul National University Hospital in Jongno-gu. Photo by Lim Hye-seon lhsro@

The optimal sleep duration for good health is 8 to 9 hours for adolescents and 7 to 8 hours for adults. So, are there ways to improve sleep quality? First, avoid using smart devices in bed. The LED light from smart devices contains a high amount of blue light near 480 nm wavelength. This blue wavelength suppresses the secretion of the hormone melatonin, which regulates activity cycles. This is because photosensitive retinal ganglion cells in the eye's retina, which send signals to the suprachiasmatic nucleus of the optic nerve, are most sensitive to 480 nm. Melatonin removes reactive oxygen species in our body and neutralizes the toxicity of oxygen used in respiration. Professor Jeong explained, "If elementary school students, who are in a rapid growth phase, use smart devices before sleep, it can cause long-term health problems," adding, "Smart devices should be avoided at least 2 hours before bedtime."

Maintaining a regular lifestyle is also important. Wake-up times should be consistent. Sleeping in on weekends to compensate for lack of sleep during weekdays disrupts the body's rhythm. It is better to wake up at the same time even on weekends. Temperature is also closely related. Professor Jeong said, "It is good to keep hands and feet warm and the bedroom slightly cool," adding, "If the core body temperature does not drop, it is difficult to switch to sleep mode even if sleep pressure is high." He continued, "The recommended bedroom temperature is 16 to 18 degrees Celsius. In the morning, as the core body temperature passes its lowest point and rises to prepare for waking, the bed or bedroom temperature should be warmer than before sleep to make waking easier."