By prefecture
Sleep deviation ranking

This is a ranking of the sleep deviation scores of the 47 prefectures, based on the results of a survey of approximately 10,000 people nationwide.
Aomori Prefecture, which ranked first, has good quality sleep and good habits, and many people do not feel sleepy during the day. It also ranked third in the nation for the length of sleep.
On the other hand, Miyagi Prefecture, which ranked last, did not stand out in terms of short sleep time, but had poor sleep habits, health status, and stress. It also had the highest number of people at risk of sleep apnea syndrome, a type of sleep disorder, in the prefecture nationwide.

Average sleep time in Japan

"Sleep debt is leading to bankruptcy in Japan"

In recent years, chronic lack of sleep has ballooned like a debt that is difficult to repay. This "sleep debt" is not only prevalent among business people, but also among housewives and children, and immediate measures are necessary.
It has become clear that sleep is not just rest or a release from sleepiness, but also plays an important role in regulating the autonomic nervous system and hormone balance, solidifying memories, enhancing immune function, removing waste products from the brain, etc. Without adequate sleep, the risk of developing lifestyle-related diseases such as obesity, diabetes, and high blood pressure, as well as mental illness, infectious diseases, cancer, and dementia, increases.
It is difficult to significantly increase the amount of sleep you get while working, but even sleeping 15 minutes longer each day can have an effect. Let's try to improve Japan's broken sleep system.

Survey results

Sleep time 55 minutes shorter than the worst one

Average sleep time in Japan

Results Summary

According to a 2018 OECD survey, the average sleep time of Japanese people was 7 hours and 22 minutes, the shortest in the world. In recent years, sleep time has become even shorter due to the 24-hour society, and it was reported that 40% of the Japanese population sleeps less than 6 hours.
The results of this survey showed that the average sleep time of Japanese people is 6 hours and 27 minutes, which is 55 minutes shorter than when they were said to be the worst in the world.
It can be said that Japan today is not only accumulating "sleep debt," but is also heading toward collapse.

SAS Risk and
Relationship between BMI value

Sleep apnea syndrome (SAS)
22 % of people are at high risk

Sleep apnea syndrome, which requires medical treatment, is a typical example of a sleep disorder. As the name suggests, it is a disease in which "apnea" occurs repeatedly during "sleep," disrupting sleep. It is also called "SAS," an acronym for the English name Sleep Apnea Syndrome. In this disease, "apnea" is counted as one episode when breathing stops for 10 seconds or more, and the number of times breathing stops per hour is used as an indicator. People suffering from moderate or severe SAS (respiratory cessation more than 15 times per hour) have a 2-4 times higher risk of myocardial infarction and cerebral infarction than normal, and there is frightening data that shows that about 40% of people who leave it untreated die within about 8 years. Causes of SAS include fat deposits around the soft parts of the upper airway such as the neck and throat due to weight gain, enlarged tonsils, and narrowing of the throat and upper airway due to the base of the tongue and uvula.
This may give the impression that this is a disease that affects obese men, however, Asians tend to have narrow airways due to the small, set-back jaw, so it is important to remember that even thin people, women, and children can suffer from this disease.
This survey found that 22% of Japanese people are at high risk of suffering from sleep apnea syndrome.

Survey results

Distribution of BMI and sleep deviation/sleep time of people at high risk of SAS

Overall distribution and sleep deviation score/sleep time

This study once again found that the higher the BMI, the higher the risk of SAS.
98% of people at high risk for SAS said they had been told they snore. In addition, 68% of people at high risk for SAS had gained 10kg or more since they were 20 years old.

Simple SAS check

Sleep Standard Deviation by Occupation

"Young managers' sleep is dangerous"

In some professions, people who work night shifts or reversed day and night shifts are unable to get quality sleep and struggle with sleep debt.
Many people may think that a little bit of sleep deprivation is unavoidable because they are busy every day, but sleep debt should not be taken lightly.
A person may fall asleep momentarily during work hours without even realizing it. If they lose consciousness while working, it could lead to an unexpected accident.
In order to reduce sleep debt even as much as possible, it is also important to organize your shifts in an innovative way and take naps during the day.

Survey results

Sleep deviation score by occupation

Results Summary

Looking at the data by age and occupation, people working in construction and mining had the lowest sleep deviation score of 43.83.
In addition, professional drivers, one of the occupations often seen in the news as having a high incidence of accidents during work hours related to lack of sleep, also had a sleep deviation score of 44.64, second only to construction and mining.
Another noteworthy point is that there was a large difference in the sleep deviation score of "CEOs and executives" depending on their generation. While the sleep deviation score of CEOs and executives in their 50s and 60s was 50.16, which was higher than the average, CEOs and executives in their 20s had the lowest sleep deviation score of all, at 35.77. In terms of sleep time, the average was 5 hours and 32 minutes, which was 1 hour and 50 minutes shorter than the average of 7 hours and 22 minutes in the OECD (2018) survey.

Awareness of naps

"67% of Japanese people feel sleepy during the day"

You can't get a good night's sleep, you have trouble waking up in the morning, you feel very sleepy during the day... These problems may be caused by an underlying illness.
A typical sleep-related illness is sleep apnea syndrome (SAS). If you think you may have sleep apnea syndrome, we recommend that you visit a nearby sleep clinic.
Even if you don't have a sleep disorder, taking a nap during the day if you feel sleepy can be effective. A 20-minute nap up until around 3pm doesn't affect the quality of your sleep at night, and tends to be more effective at relieving daytime sleepiness. It has also been reported that people who take naps of less than 30 minutes have a dementia incidence rate of about one-sixth of those who don't have the habit of taking naps.

Survey results

Age distribution of people wanting to take a nap

Desire to take a nap and sleep deviation score

The percentage of people who felt sleepy during the day and wanted to take a nap was high in all age groups, accounting for 67% of the total across all age groups. It was also found that people who wanted to take a nap had a lower-than-average sleep deviation score.

Sleep deviation score
Top and worst lifestyle habits

Of approximately 10,000 people nationwide, the lifestyle habits of the top 1,000 with the best sleep scores and the worst 1,000 with the worst sleep scores were revealed.

Sleep and Food

Eating habits showed a big difference: 79% of the Top 1000 eat breakfast seven days a week, compared to just 52% of the Worst 1000.
While 83% of the TOP 1000 answered that they do not eat late-night snacks, only 39% of the WORST 1000 answered that they do not eat late-night snacks, meaning that 61% of people eat late-night snacks, with 13% of them eating late-night snacks every day, 7 days a week.

Frequency of eating breakfast and late-night snacks
Q: How many days a week do you do this?

breakfast

• All Japanese people

  

• Top 1000

  

• Worst 1000

  

Late-night snack

• All Japanese people

  

• Top 1000

  

• Worst 1000

  

Eating breakfast not only raises your body temperature, regulates your daily rhythm, and replenishes your energy for activities, but also resets your body clock. Chewing your food well stimulates your brain, making it easier to balance between wakefulness and sleep.
Eating late at night will activate your stomach and lead to poor quality sleep.

Sleep and alcohol

42% of the TOP1000 do not drink alcohol at all, and only 28% drink it 3 or more days. In terms of quantity, only 19% drink 2 or more cups of alcohol. On the other hand, in the WORST1000, only 29% do not drink alcohol, and 42% drink alcohol 3 or more days a week. In terms of quantity when drinking, 44% drink 2 or more cups of alcohol, and 6% drink 5 or more cups of alcohol.

Alcohol intake frequency and amount
Q: How many days a week do you drink alcohol and how much do you drink?

frequency

• All Japanese people

  

• Top 1000

  

• Worst 1000

  

amount

• All Japanese people

  

• Top 1000

  

• Worst 1000

  

Excessive drinking makes sleep shallow and has a diuretic effect, which can wake you up in the middle of the night and reduce the quality of your sleep. On the other hand, alcohol has the effect of relaxing an excited brain. Drinking weak alcohol for a long period of time is a no-no. One cup of sake is fine 100 minutes before going to bed, and one sip of strong alcohol just before going to bed is OK. It is also important to know how to deal with the alcohol content of your drinks.

Sleep and smoking

There were also big differences in smoking status, with 92% of the TOP1000 not currently smoking.
On the other hand, 43% of the WORST 1000 were smokers, and 29% of them smoked 10 or more cigarettes a day.

Amount of smoking
Q: How many cigarettes do you smoke per day?

• All Japanese people

  

• Top 1000

  

• Worst 1000

  

Nicotine, the main component of tobacco, has a stimulant effect and can reduce the quality of your sleep.
When you quit smoking, the function of a neurotransmitter called acetylcholine returns to normal, helping you get better quality sleep.

Sleep and environment

Although the differences were not as big as in the other categories, 77% of the TOP1000 slept in a completely dark environment, while the WORST1000 only accounted for 60%.

environment
(Q: How often do you sleep in a quiet, dark room?)

• All Japanese people

  

• Top 1000

  

• Worst 1000

  

environment
(Q: How bright is the room when you go to sleep?)

• All Japanese people

  

• Top 1000

  

• Worst 1000

  

It is said that the key to deep sleep is "light." Melatonin, a hormone that promotes sleep, has the characteristic that its secretion is momentarily inhibited by strong light. In humans, the only organ that detects light is the eye, so it is necessary to consciously limit visual information before going to sleep.
For room lighting, warm reddish lights that are closer to sunlight are more suitable for a bedroom than the pale light of fluorescent lights or LEDs. Also, indirect lighting that illuminates the floor can reduce visual information when going to bed. Also, the bright lights in convenience stores are very strong light stimuli, so it is not advisable to visit them before going to bed at night.