"Do I have to sleep for 8 hours?" Sleep quality and cycles are more important than sleep duration

Many people feel an obsession that they must sleep for exactly 8 hours for the sake of their health. However, it has been confirmed through medical evidence that sleep quality and an individual's appropriate cycle are more important than the amount (duration) of sleep. Professor Kim Hye Yoon of the Department of Neurology at Catholic Kwandong University International St. Mary's Hospital corrected common misconceptions about sleep through a video on the medical channel After the Rain.

The '90-minute sleep cycle' is more important than the 8-hour sleep obsession

The most common question is, "How many hours should I sleep per day?" While many consider 7 to 8 hours of sleep a mandatory condition, Professor Kim Hye Yoon explains that it is not necessary to fill exactly 8 hours. Citing research from Harvard and UCLA, she emphasized that quality is more important than the quantity of sleep.

The reason lies in the human sleep cycle. Generally, a sleep cycle takes about 90 minutes, and typically 4 to 6 cycles repeat during one night. If one can achieve very high-quality sleep for 6 hours while considering the 90-minute cycle, it can be a much more efficient and scientific way to sleep than trying to force oneself to fill 8 hours. Additionally, sleep duration varies by individual depending on age and hormonal changes; in the case of women, sleep duration can change according to the menstrual cycle, so it is important to accept these changes naturally.

The misconception that more sleep equals better health and the truth about alcohol

It is true that sleep is important for immunity and cardiovascular health. In fact, according to COVID-19 vaccination studies, groups that secured sufficient sleep duration showed better vaccine effects, such as producing more antibodies. However, sleeping more does not unconditionally make one healthier. According to recent research, consistently sleeping excessively for more than 10 to 11 hours can actually pose health risks.

However, an increase in sleep duration when suffering from illnesses such as body aches or the flu is a natural phenomenon where the body's defense mechanism is working. The problem is intentionally lying down excessively even when there is no illness. Since there may be serious sleep disorders such as Kleine–Levin syndrome in rare cases, excessive sleep that cannot be controlled by oneself should be discussed with a specialist.

Furthermore, the habit of drinking alcohol because one cannot sleep is very dangerous. While alcohol may initially feel like it helps one fall asleep quickly, providing a positive experience, this is an illusion. Alcohol interferes with 'REM (Rapid Eye Movement) sleep,' the stage where dreaming occurs, and causes sleep fragmentation (interruptions). When the sleep cycle is broken, one must start a new cycle again, making it impossible to achieve deep sleep, which ultimately leads to a sharp decline in sleep quality. In the long term, it can lead to alcohol addiction and decreased liver function, so 'a glass of alcohol for a good night's sleep' does not exist. Alcohol negatively affects not only the liver but also both the quality and quantity of sleep.

Napping can help concentration and cardiovascular health if done correctly

While some view napping as a symbol of laziness, napping done in the correct way is beneficial to health. There are two conditions for 'correct napping' recommended by Professor Kim. First, it should be taken around 2 PM, and second, it should be a short nap of less than 20 minutes.

If a nap exceeds 30 minutes, it can affect the sleep cycle of the night sleep. This is because if a nap is too long or taken too late, it has the effect of eating away at the nocturnal sleep cycle. A short nap that meets the recommended conditions can improve memory and concentration, and help relieve stress and improve cardiovascular health. Especially in cases where one has not slept enough at night, such a short nap can serve as a physical compensation.