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It's common for people to complain about their sleep, saying things like, "I sleep enough, but I'm still tired," or "I don't feel like I've slept well." It's certainly frustrating when you get enough sleep but still don't feel refreshed.
However, the reason for this might be that you're not getting your ideal amount of sleep. This article will explain everything you need to know about ideal sleep duration. By reading this article, you'll be able to determine your ideal sleep duration and achieve more satisfying sleep.
Ideal Sleep Duration Varies by Individual
The ideal amount of sleep varies from person to person. Some people find 6 hours of sleep ideal, while others find 8 hours ideal. Additionally, for Japanese people, who generally sleep less than people in other countries, it can be difficult to secure enough sleep due to work or household chores.
In fact, the "2019 National Health and Nutrition Survey Report" published by the Ministry of Health, Labour and Welfare reveals that approximately 35-50% of people in their working years (20-59 years old) sleep less than 6 hours, and about 5-12% sleep less than 5 hours.
Furthermore, the Survey on Time Use and Leisure Activities shows that Japanese people's sleep duration has been continuously decreasing over the past 20 years*1, and considering that the necessary sleep duration also varies by season*2, it becomes even more difficult to determine the ideal sleep duration. However, a cohort study targeting the general Japanese population concluded that 7 hours of sleep is ideal.*3
In other words, it was found that 7 hours of sleep is associated with a lower mortality risk than 4 hours or 10 hours of sleep. The difference in mortality rates was particularly significant compared to those who slept for long hours.
Regarding seasonal variations in sleep duration, due to the influence of daylight hours (time from sunrise to sunset), the average sleep duration is known to be about 10 to 40 minutes longer in winter than in summer.*2
References
*1: Significance of Healthy Sleep | e-Health Net (Ministry of Health, Labour and Welfare)
*2: Sleep Guidelines for Health Promotion 2023 | Ministry of Health, Labour and Welfare
*3: Association Between Sleep Duration and Mortality Risk | National Cancer Center Research Institute
What is a Guideline for Ideal Sleep Duration?
Taking into account the information presented so far, it is generally good to aim for around 7 hours of sleep as a guideline. Furthermore, the Ministry of Health, Labour and Welfare's "Sleep Guidelines for Health Promotion 2023" also states that 6-8 hours is appropriate.
However, this is only a general standard, and the ideal sleep duration varies from person to person. If you sleep 6-8 hours but still feel sleepy during the day and can't concentrate on work or studies, it means you are not getting your ideal amount of sleep.
Additionally, "sleep quality" is strictly related to sleep duration, so please refer to this article for details.
Summary of the "Best Sleep Method" 10 Rules for Improving Sleep Quality
Is There a Way to Find Your Optimal Sleep Duration?
We've discussed that the ideal sleep duration for adults is 6-8 hours, and within that range, the optimal sleep duration varies by individual.
Also, due to constitutional differences, such as being a "short sleeper" or a "long sleeper," some people may be able to be active and energetic during the day with less sleep, while others may require more sleep.
Whether you are getting an appropriate amount of sleep can be judged by whether you feel sufficiently rested after sleeping (the sensation of having rested through sleep) and whether you can maintain an adequate level of alertness during the day without feeling drowsy.
If you experience drowsiness during the day or don't feel adequately rested, it may be necessary to try to get more sleep or improve your sleep quality.
Precautions for Securing Ideal Sleep Duration
Even if you have a rough idea of your ideal sleep duration, improving sleep habits is tricky because it doesn't happen overnight. Just because you get your ideal amount of sleep today doesn't mean you'll maintain adequate alertness tomorrow.
However, if you're not getting your ideal amount of sleep, you'll accumulate a "sleep debt," a deficit in sleep that you might not even notice.
Sleep debt is a state where chronic sleep deprivation due to insufficient sleep over several days leads to a worsening of physical and mental health.
Sleep debt cannot be resolved by "catching up on sleep" on weekends and is typically said to take a week of repayment to return to normal. Therefore, to maintain physical and mental health, it is necessary to understand and secure your ideal sleep duration.
You need to adjust your sleep time little by little
To ensure ideal sleep, the Ministry of Health, Labour and Welfare recommends sleeping at least 6 hours on weekdays. If this is difficult, getting slightly longer sleep in the middle of the week or on weekends can help prevent the accumulation of sleep debt.
However, some people may have gotten used to sleeping less than 6 hours and find it difficult to fall asleep earlier, even if they try.
In such cases, it is important to adjust by gradually increasing sleep duration each day. Aim to repay and adjust little by little every day, rather than just trying to get ideal sleep the night before an important event.
Address the causes preventing you from getting ideal sleep
To secure your ideal sleep duration, you need to understand why you haven't been able to secure it until now.
If work is the cause, finish it earlier. If gaming is the cause, set a time limit for it. Address each cause that prevents you from getting enough sleep.
Also, if you "can't fall asleep easily at bedtime" or "feel sleepy or tired during the day despite getting what should be your ideal sleep duration," your body clock may be disrupted.
The body clock is the body's mechanism that creates a daily rhythm, such as waking up in the morning, being active during the day, and feeling sleepy at night.
When the body clock is disrupted, the sleep cycle, including REM and non-REM sleep, also gets disturbed, leading to problems such as difficulty falling asleep even with ideal sleep duration, or shallow sleep that doesn't provide adequate rest.
To regulate your body clock, it's important to maintain a regular lifestyle, such as exposing yourself to morning sunlight, going to bed and waking up at consistent times, eating three meals a day at regular times, and getting moderate exercise.
In addition, blue light emitted from smartphones and computers can also disrupt the body clock. To allow your body to prepare for sleep, try to avoid using these devices 90 minutes before bedtime.
3 Ways to Ensure Ideal Sleep Duration
Let's look at what else you can do to ensure you get enough sleep. Once you decide what to do, all you have to do is follow those rules. It might be difficult to do everything from the start, so it's easier to continue if you start with what you can do.
Keep a sleep diary
Keeping a sleep diary is effective for achieving your ideal sleep duration. It allows you to understand your current sleep patterns and makes it easier to find your optimal sleep duration.
The method is simple: just record "time got into bed," "time fell asleep," "time woke up," and "time got out of bed" every day. It's even better if you also record whether you felt drowsy during the day.
For those who find keeping a sleep diary bothersome, smartphone apps or wrist-worn activity trackers are recommended. Their performance has advanced, and they can automatically record sleep-wake rhythms. You can objectively grasp your actual sleep state and analyze it with data, not just subjective feelings. Based on the recorded data, aim to secure your ideal sleep duration.
Regulate your body clock
To adjust your body clock, which significantly impacts your sleep rhythm and quality, exposing yourself to morning sunlight every day is effective.
In fact, the human body clock operates on a cycle of 25 hours, which is a 1-hour discrepancy from Earth's 24-hour rotation. However, morning light contains components that advance the body clock, so exposure to morning sunlight resets it, leading to comfortable sleep at night.
Other effective ways to adjust your body clock include maintaining consistent wake-up and bedtime, and eating three meals a day at the same time. In particular, late-night meals can disrupt the body clock, so try to finish dinner by 8 PM at the latest.
Pay attention to how you spend time before sleep
Paying attention to the time before bed can help you fall asleep more easily.
Avoiding stimulating activities like gaming, using smartphones, or computers and instead creating a relaxed environment can improve sleep quality. Try diffusing relaxing essential oils like lavender or other favorite scents, or playing calming, slow-tempo sleep music.
Also, the lower your core body temperature, the easier it is to fall asleep. Therefore, taking a bath at least 90 minutes before bed can help you fall asleep smoothly.
For other recommended ways to spend your time before bed, please refer to the article below.
【Doctor Supervised】8 Ways to Fall Asleep Instantly! Practice on Your Bed Tonight
Focus on Sleep Quality as well as Sleep Duration
Sleep isn't just about how long you sleep; its quality, or how deeply you sleep, is also crucial.
Even with the same amount of sleep, high sleep quality allows your body and brain to rest efficiently, leading to a refreshed awakening and high performance during the day.
To improve sleep quality, in addition to the pre-sleep routines and body clock adjustments mentioned above, it's recommended to pay attention to your bedroom environment and bedding.
Brain Sleep develops and sells various bedding products, including pillows and mattresses, which significantly impact sleep quality, as well as other products that enhance sleep quality. Please find the one that suits you best.
Be Careful Not to Oversleep
While sleep deprivation is detrimental to health, oversleeping is also not good.
If you try to compensate for sleep deprivation all at once by oversleeping, it can disrupt your sleep rhythm or cause headaches from oversleeping, leading to adverse effects.
What causes headaches from oversleeping? How to treat and prevent them by type
If your sleep duration on holidays is more than 2 hours longer than on weekdays, it's highly likely that you've accumulated sleep debt during the week. Review your bedtime and daily routine, and strive to understand and secure the appropriate amount of sleep for yourself.
Achieve Your Ideal Sleep Duration! Check Out Recommended Items
Brain Sleep develops various bedding products to meet our customers' sleep needs and concerns. Here, we introduce the features and highlights of our recommended items.
Aim for Ideal Sleep Duration for a Healthy Daily Life
First and foremost, it's important to understand your ideal sleep duration. Consider how much sleep is right for you and try to get that amount. However, it's not as simple as just sleeping longer, so be careful. Here's a summary of this article:
- Ideal sleep duration varies by individual.
- For most people, the ideal sleep duration is about 6-8 hours.
- Sleep habits cannot be changed immediately.
- It's important to identify the reasons why you can't get your ideal sleep duration.
- Also pay attention to the time before falling asleep.
Even if you manage to get your ideal sleep duration, it's meaningless if you don't maintain it. If it has become a habit, it can be difficult to change it suddenly. Try to improve it gradually, over time.
