Log in
Autumn, with its pleasant evening breezes, is the season for sound sleep. Japanese people, who are busy with both work and private life, reportedly have a low "sleep health score" compared to the rest of the world, with many not getting enough sleep. What kind of ailments can occur in our brains and bodies if we sacrifice sleep to prioritize a large number of tasks?
Here are some sleep trivia that you might not know, even if you think you do.
Is Japan's Sleep Health Score the Lowest in the World? Ideal Sleep Duration and Quality
According to some statistical data, the average sleep duration for Japanese people is 6.5 hours. It is said that approximately 40% of them sleep less than 6 hours. This is considered a short amount of sleep even in America.
Furthermore, even Japanese people who sleep less than 6 hours reportedly desire to sleep for "about 7.2 hours," and the difference between "desired sleep duration" and "actual sleep duration" is said to be larger compared to other countries.
However, this doesn't mean that one should simply abandon all responsibilities and sleep as much as possible.
In fact, there is data suggesting that "sleeping too long can actually be detrimental to the body." What is important is "quality" over "quantity." It is sufficient to ensure the necessary sleep duration to achieve good quality sleep that benefits both mind and body.
Incidentally, sleep duration varies with age and shortens as one gets older.
It is often said that 8 hours of sleep is ideal, but that is only until early adolescence. For those in their prime working years around 25, 7 hours is said to be the norm, so it seems that the current reality is still a slight lack of sleep.
What Happens if Sleep Deprivation Continues? Six Unexpected Sleep-Related Problems
What kind of problems can occur if you don't get enough sleep? Here, we introduce six "sleep problems" that will make you wonder, "How is this related to sleep?"
1. You gain weight more easily
According to a research report from Columbia University in the U.S., it was found that people who slept 6 hours were 23% more likely to be obese, those who slept 5 hours were 50% more likely, and those who slept 4 hours or less were 73% more likely, compared to people who slept an average of 7-9 hours. The shorter the sleep duration, the higher the probability of obesity.
This is due to hormones secreted during sleep. When you sleep well, the secretion of "growth hormone" and "cortisol," which break down fat, and "leptin," which suppresses appetite, increases. Conversely, the secretion of "ghrelin," which stimulates appetite, decreases.
In other words, when you are sleep-deprived, you tend to eat more, and since fat is not broken down effectively, you become more prone to obesity.
2. Emotions become unstable and thoughtless
When sleep-deprived, people tend to be irritable and easily overwhelmed by their own feelings.
Without the mental space to consider the feelings of others, they may express their emotions more directly compared to those who sleep well, which can disrupt interpersonal relationships.
Be careful if you notice signs like "I've been irritable lately," "I can't communicate well with those around me," or "I've been making more careless mistakes!" It would be unbearable to be thought of as a "small-minded person" due to lack of sleep.
3. Increased risk of dementia
The brain is the most active organ, and the more it is used, the more waste products accumulate. For example, amyloid beta, one of the causative agents of Alzheimer's dementia, is normally broken down and expelled in a healthy brain that gets adequate sleep.
However, if there is not enough sleep, it cannot be properly expelled and accumulates in the brain, increasing the risk of Alzheimer's dementia. Also, although the brain does not have a lymphatic system, it is equipped with a special system for discarding waste products that replaces it, and most of the brain's waste products are excreted during sleep. There are reports that waste products are excreted 4 to 10 times more efficiently during sleep than during wakefulness.
To maintain our individuality until the last day of our lives, it's important to establish a regular habit of getting enough sleep.
4. Work performance decreases
According to a research study in the U.S. on "the relationship between sleep duration and academic performance" conducted on 120 high school students, students who slept longer, around 7.5 hours, and went to bed earlier, around 10:30 PM, had better academic results.
In reality, if you don't get enough sleep, everything you do becomes slower, your memory deteriorates, and you can't come up with good ideas, leading to a steady decline in work performance. If you want to achieve good results at work, you should not underestimate the importance of sleep.
5. Increased risk of infections and allergies
The immune system is closely linked to sleep because it interacts with hormones and circadian rhythms.
When sleep is inadequate, hormonal balance is disrupted, and immune function goes awry, increasing the risk of immune-related illnesses such as colds, influenza, and cancer. Additionally, a weakened immune system can worsen allergies like hay fever and atopic dermatitis.
6. Mortality rate increases
Recent reports indicate that insufficient sleep increases the risk of prostate cancer and breast cancer. Even in healthy individuals, atypical cells, which are prone to becoming cancerous, are produced at a certain rate, but they are removed by the immune system. Therefore, a weakened immune system increases the risk of cancer.
It is known that sleep deprivation and poor sleep quality are causes of various life-threatening diseases such as cancer, heart disease, and high blood pressure. Various research data related to sleep and health have been reported, such as "middle-aged and elderly people who sleep less than 5 hours a day have twice the incidence of high blood pressure compared to those who sleep 7-8 hours."
Growth hormone, which is secreted in higher amounts during deep sleep, promotes metabolism and repairs damaged cells. Additionally, sleep is involved in the removal of atypical cells that can lead to cancer, through enhanced immune function and the secretion of hormones related to body repair during sleep. Therefore, getting enough sleep helps to attack cancer cells.
Furthermore, the repair of blood vessels damaged by high blood pressure occurs when blood pressure is low during sleep. In this way, sufficient sleep is essential for maintaining a healthy body for a long time.
Practice Tonight! 3 Simple Tips to Improve Sleep Quality
Here are some simple routines to help you get good quality sleep.
1. Perform a "sleep ritual"
By ritualizing actions before sleep, such as "gradually turning off lights as bedtime approaches," "burning aromatherapy," "changing into pajamas," or "listening to classical music," you can naturally switch from an awakened ON mode to an OFF mode, relaxing your mind and body and making it easier to fall asleep.
2. Focus on the first 90 minutes of sleep
Sleep is deepest at the beginning, and about 80% of growth hormone is secreted during the first 90 minutes of sleep.
If you don't sleep well during these first 90 minutes, your sleep quality will suffer, meaning you might not wake up feeling refreshed no matter how many hours you sleep afterward. So be careful.
3. Increase serotonin levels
Serotonin is essential for good quality sleep, as it is also the raw material for the sleep hormone melatonin. By actively engaging in activities during the day such as "getting plenty of morning sunlight," "doing light exercise," and "interacting with people," you can increase serotonin levels and sleep soundly at night. Serotonin synthesis is promoted by sunlight exposure, while melatonin synthesis is inhibited by light. It is important to have a clear distinction and switch between night and day. Be careful not to expose yourself to light at night, as this can make it even harder to sleep and lead to an unhealthy state.
While this season is perfect for enjoying relaxing evenings, staying up late enough to cut into your sleep time can significantly lower your sleep quality. For a healthy mind and body, and a happy future, let's fully enjoy a fulfilling sleep life!
While there is a term "sleep ritual," it's important not to ritualize things without reason, but rather to understand the mechanisms of sleep and biological rhythms and then adopt habits that are good for your sleep. I specifically use the term "positive routines" to describe such habits for deep sleep.
What works for you might not work for others, and what works for others might not necessarily work for everyone. Since sleep habits vary individually, it's crucial to find the optimal solution for yourself.
