[News in Numbers] Korean Sleep Quality Scores... Lower Than the Global Average

A survey revealed that the quality of sleep among Koreans is lower than the global average.

According to the '2024 Garmin Connect Data Report' released by the U.S. smart device company Garmin, Korea scored below average in sleep quality, as indicated by the sleep score. The global average sleep score this year was 71 points, considered 'average.' Korea scored 66 points, 5 points lower. The country with the best sleep quality was the Netherlands (73 points), while the country with the worst sleep quality was Indonesia (64 points). According to 2016 statistics 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 average of 8 hours and 22 minutes, ranking the lowest.

Professor Jeong Ki-young, a sleep medicine specialist at Seoul National University Hospital who has treated various patients over 25 years, stated, "As the U.S. has declared sleep problems as a public health issue like an epidemic or pollution, sleep is a societal issue beyond an individual problem." He pointed out, "Considering that Korea ranks first in the world for suicide rates, the quality of sleep among Koreans is the lowest." People tend to underestimate sleep problems, judging that reducing a few hours of sleep will not significantly affect their health. However, even one night of poor sleep greatly impacts both body and mind. Professor Jeong said, "In the short term, stress responses increase, and blood pressure and blood sugar levels rise," adding, "Emotionally, people become easily irritable, and anxiety or depression increases." In the long term, he noted, "The risks of obesity, metabolic syndrome, hypertension, diabetes, heart disease, and stroke increase."

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 emitted 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 the activity cycle. This is because photosensitive retinal ganglion cells in the retina, which send signals to the suprachiasmatic nucleus of the optic nerve, are most sensitive to 480 nm. Melatonin helps remove reactive oxygen species in our body and neutralizes the toxicity of oxygen used in respiration. The recommended bedroom temperature is 16 to 18 degrees Celsius. In the morning, as the core body temperature rises after reaching its lowest point, the bed or bedroom temperature should be warmer than before sleep to make waking up easier.

Meanwhile, the global average 'Body Battery' score, which indicates an individual's energy level throughout the day, was 71 points. The report included analysis information on global health and fitness activities. Korea scored 68 points. The highest Body Battery score was recorded in the Netherlands (74 points), while the lowest was in Japan with 66 points.

However, the number of steps taken was relatively high. The global average daily step count among Garmin users was 8,317 steps. Koreans walked more, averaging 9,210 steps. The country with the highest step count was Hong Kong, recording 10,340 steps. Stress levels were also included in the report. Korea scored 28 points, slightly lower than the global average of 30 points. In contrast, the country with the highest stress level was Malaysia (33 points).