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March 13 – World Sleep Day

A normal sleep cycle repeats deep and light sleep five to seven times, and adults are recommended to sleep 7 to 9 hours per night.

Humans spend about one-third of their lives sleeping. Sleep is not merely a state of rest. It is a vital physiological process that restores both the brain and the body, essential for sustaining life. During sleep, damaged cells are repaired, memories are organized, and the immune system is strengthened.

Despite this, modern people often choose sleep as the first thing to sacrifice. With overtime work, academic pressure, and late-night smartphone use becoming routine, sleep deprivation has become a common part of daily life. Chronic lack of sleep can lead to weakened immunity, metabolic disorders, increased risk of cardiovascular disease, and mental health problems such as depression and anxiety.

As World Sleep Day on March 13 approaches, it is a good time to reconsider the value of sleep.

When You Don’t Get Enough Sleep, Your Focus and Memory Decline

Park Ji-hee (36), an office worker, has recently struggled to get deep sleep. After lying in bed, she often watches videos or browses social media on her smartphone, frequently staying up until 2 a.m. Her average sleep time is now barely four hours per night.

“Even when I manage to fall asleep, I wake up feeling foggy in the morning,” she said. “During the day, I feel sleepy and exhausted, which makes it hard to focus at work.”

When sleep becomes insufficient, the body accumulates what experts call “sleep debt.” When this debt builds up, the “interest” we pay appears as declining concentration, memory, and cognitive ability.

Irregular sleep habits can also negatively affect blood vessels and heart health. Overactivation of the sympathetic nervous system raises blood pressure and increases the risk of cardiovascular disease. Blood sugar control becomes more difficult, which can lead to weight gain and chronic inflammation, creating the foundation for various health problems.

Sleep Follows a Natural Pattern

Sleep occurs in cycles consisting of deep sleep (non-REM sleep) and light sleep (REM sleep), typically repeating five to seven times per night.

When this balance is disrupted, brain health and emotional stability can suffer.

Professor Yoon Ji-eun, a neurologist at Soonchunhyang University Bucheon Hospital, explains:

“Deep sleep is responsible for physical recovery, immune strengthening, and waste removal from the body.
REM sleep, when the eyes move rapidly and dreams occur, plays an important role in emotional regulation and memory consolidation.”

How Much Sleep Is Enough?

The ideal amount of sleep varies from person to person and also changes with age. Generally, sleep requirements decrease as people get older.

According to the Korean Sleep Research Society, adults should aim for 7 to 9 hours of sleep per night. Sleeping significantly less—or even more than an hour beyond this range—may not be beneficial. For optimal health, getting at least seven hours of sleep is recommended.

However, even if you sleep long enough, poor sleep quality means you may still wake up feeling unrefreshed.

If sleep patterns are irregular, people are more likely to feel sleepy during the day or suffer from insomnia at night. A stable circadian rhythm is essential so the body remains active during the day and naturally falls asleep at night.

This is why sleeping excessively on weekends to “catch up” can actually make people feel even more tired.

Sleep Apnea: A Major Cause of Poor Sleep Quality

One of the most common conditions that reduces sleep quality is sleep apnea. This disorder occurs when breathing repeatedly stops or becomes shallow for more than 10 seconds during sleep.

Repeated breathing interruptions lower blood oxygen levels, causing the brain to repeatedly awaken and preventing deep sleep.

Professor Na Jin-oh from the Department of Cardiology at Korea University Guro Hospital warns:

“Sleep apnea can lead to complications such as high blood pressure, heart failure, cognitive impairment, and even depression. Proper diagnosis and treatment are important. A sleep study is needed for an accurate diagnosis.”

Don’t Sleep Face Down — And Avoid Long Naps

Sleep posture also matters. Sleeping face down or with a misaligned spine can cause pain, which in turn interferes with restful sleep.

Dr. Lee Dong-chan, a neurosurgeon at Mokdong Himchan Hospital, advises:

• When lying on your back, use a pillow of appropriate height and place a small pillow under your knees to relax the lower back.
• When lying on your side, use a pillow that matches shoulder height and place a pillow between your legs to reduce pressure on the spine.

The Key to Good Sleep Is Consistency

Most sleep problems are related to irregular sleep habits. Maintaining a consistent wake-up time is particularly important. Even if you slept poorly the night before, getting up at the same time helps stabilize your body’s biological rhythm.

Healthy sleep habits include:

• Get enough sunlight during the day
• Finish exercise 3–4 hours before bedtime
• Avoid naps, or limit them to 15–30 minutes
• Avoid caffeine and nicotine in the late afternoon
• Limit alcohol, which disrupts deep sleep
• Reduce smartphone and TV use two hours before bedtime
• Keep the bedroom quiet, dark, and comfortable

The ideal bedroom environment is a temperature of 16–20°C (60–68°F) and humidity of 30–50%.

If you cannot fall asleep, avoid staying in bed for long periods while awake. Instead, move to a quiet place and engage in low-stimulus activities such as light reading or listening to the radio until you feel sleepy again.

 

Source: 중앙일보 (https://www.joongang.co.kr/article/25410163)