Is sleeping in bad for your health? A thorough explanation of the causes and countermeasures of sleeping in

When you wake up to an alarm but fall back asleep, it's called "nidone" (sleeping in again). I'm sure you've all experienced this.

I'm not a morning person and almost always sleep in again. Does this affect my health? ... This article explains the reasons why people sleep in again and tips to prevent it for those who have such concerns.

Is "Nidone" (sleeping in again) bad for your body?

The autonomic nervous system consists of two types of nerves: the "sympathetic nervous system," which is active during the day and when you're active, and the "parasympathetic nervous system," which is active at night and when you're relaxed. The balance between these two types of nerves affects your physical and mental well-being. When the autonomic nervous system is disturbed, it can lead not only to insomnia and poor sleep quality but also to various symptoms both mentally and physically, such as anxiety, tension, sluggishness, headaches, and stiff shoulders.

Is there such a thing as "good nidone"?

Generally, sleeping in again is considered bad for your body, but it is also said that if it's for a short time and only once, then sleeping in again can be good.

When you wake up to an alarm but then turn it off and sleep in again because it's a holiday, it can feel very pleasant. At this time, a large amount of "cortisol," a hormone responsible for stress resistance, is secreted in your body. Cortisol secretion sharply increases 1-2 hours before waking up, so by sleeping in again, cortisol continues to be secreted for a longer period.

Additionally, it is said that "endorphins," which are secreted in large amounts when you hear pleasant sounds, are also secreted while you are sleeping in again. Endorphins are believed to have the effect of relieving tension and reducing stress.

However, if you sleep in again for more than 10 minutes, you enter a deep sleep that can no longer be called "nidone," so try to limit it to "just once for 5 minutes."

Causes of Sleeping in Again

Here are the common reasons why you might not be able to wake up refreshed in the morning and end up sleeping in again.

1: Sleep Deprivation

If you sleep in again due to temporary reasons like being busy with work the day before, having a drinking party, or drinking too much coffee and not feeling sleepy, resulting in late bedtime and sleep deprivation, there's no need to worry.

It's hard to say definitively as the appropriate amount of sleep varies from person to person, but if you're getting enough sleep yet still feel sleepy in the morning and sleep in again, it's possible that the poor quality of your sleep isn't allowing you to recover from fatigue. In this case, it's recommended to visualize whether you are truly getting sufficient sleep.

2: Physical and Mental Stress

If your body is fatigued from long working hours, or if you are exposed to excessive tension or stress, your autonomic nervous system may become imbalanced.

The sympathetic and parasympathetic nerves of the autonomic nervous system maintain balance by switching between each other. However, if the autonomic nervous system is disturbed, the sympathetic nervous system may remain dominant even at night, leading to difficulty falling asleep and poor sleep quality.

3: Sleep Environment

Even if you get enough sleep, a poor sleep environment can lower your sleep quality, leading to a state of sleep deprivation.

The sleep environment includes the temperature, humidity, brightness, and noise level of your bedroom, as well as whether your bedding suits you. These factors collectively greatly influence sleep quality. If these elements of your sleep environment are not in order, you may have trouble falling asleep or experience shallow sleep.

In summer, a room temperature of around 25-27°C is considered ideal, with sleep quality declining above 28°C. In winter, around 15-18°C is said to provide stable sleep, and humidity of around 50% is ideal throughout the year.

Also, be careful, as a bright room or a noisy bedroom can cause you to wake up in the middle of the night or prevent you from getting deep sleep. Another important factor is your bedding. Bedding that doesn't suit you cannot improve your sleep quality.

Disadvantages of Sleeping in Again

While I've mentioned that sleeping in again is generally not good, what exactly are its disadvantages?

1: Disruption of the Body Clock and Lifestyle Rhythm

The human body has an internal clock with a 24-hour cycle, where it's active during the day and in a resting state at night. However, since the internal clock's cycle is approximately 24.2 hours, it shifts slightly every day, requiring it to be reset.

The body clock is reset by exposure to strong light in the morning, so when you wake up, open the curtains and expose yourself to sunlight for about 15 seconds.

Because sunlight has very high illuminance, it is effective even on cloudy or rainy days. It is said that melatonin, the sleep hormone responsible for sleep, is secreted approximately 14-16 hours after exposure to strong light. Therefore, by resetting your internal clock in the morning, you will naturally feel sleepy at night and can establish a regular sleep rhythm.

Conversely, if that rhythm is disturbed, your body clock will also be disrupted, preventing you from waking up refreshed at your usual time and leading to sleeping in again. Also, sleeping in again itself can disrupt your body clock, so to avoid falling into a vicious cycle, be sure to reset your body clock properly.

2: Negative Impact on Beauty and Diet

In fact, sleeping in again also has a negative impact on beauty and diet.

If you don't get quality sleep and your body clock isn't reset properly in the morning, the secretion of growth hormone decreases, leading to a decline in metabolism. As a result, it can hinder skin regeneration, potentially leading to dull skin.

Furthermore, growth hormone also has a fat-burning effect, so a decrease in growth hormone secretion due to sleep deprivation can also worsen fat-burning efficiency.

Measures to prevent sleeping in again

Here are three measures you can take to prevent sleeping in again, which has various disadvantages.

1: Ensure Sufficient Sleep

If you keep sleeping in again, the first thing to suspect is sleep deprivation. While sleep quality is an important factor in addition to quantity, first try to ensure you get enough sleep. However, if it's difficult to get enough sleep, then focus on improving sleep quality to recover from fatigue efficiently.

2: Adjust your body clock and lifestyle rhythm

In some cases, sleeping in again is linked to a disrupted body clock and lifestyle rhythm, so first, review your daily routine.

To establish a proper lifestyle rhythm, wake up at the same time every morning, open the curtains, and expose yourself to sunlight. Eating breakfast will also raise your body temperature.

During the day, physical activity and engagement will lead to a pleasant fatigue, which in turn improves the quality of sleep at night. Try to go to bed at the same time every day, and it's also important to avoid exposure to blue light from smartphones and computer screens before sleeping.

3: Understand your sleep cycle

Waking up according to your sleep cycle can make you feel refreshed in the morning. Use "Brain Sleep Coin," an app and device that utilizes advanced AI algorithms in sleep research to understand everything about your sleep, to grasp your sleep cycle. By linking the app and device, you can get a more detailed understanding of your sleep cycle.

There are "good" and "bad" types of sleeping in again.

The cause of sleeping in again is often a lack of sleep itself, so try to review your lifestyle to ensure you get enough sleep.

If you absolutely must sleep in again, extended periods of sleeping in can disrupt your body clock and daily rhythm. Therefore, limit it to just once for 5 minutes. A 5-minute snooze can offer relaxation and stress-relief benefits, and can also help alleviate the slight sleep debt that accumulates daily.