For a good sleep.


Create your sleep.

Megumi Kaji of the Research Association of Sleep and Society points out that you create your sleep while youʼre awake. Everyone knows that you can work well on days when youʼve had a good sleep, but the opposite is also true. You get a good nightʼs sleep after a well-spent day. Sensible living and quality sleep. It seems that the two are closely linked. We asked Megumi Kaji to tell us more about creating sleep while youʼre awake.

Megumi KAJI

Megumi KAJI

Joined pillow specialist Lofty in 1989. Worked on surveys and research involving sleep and society, becoming one of the initial employees of Loftyʼs Research Institute on Sleep and Society. In 2009, went independent, planning and organizing research into sleep and society. In 2010, took responsibility for the secretariat of the Research Association of Sleep and Society. Writings related to sleep, sleepwear, and times and places for sleeping include a book Gussuri (“Sleeping Soundly,” pub. Shinchosha), written from the perspective of a sleep enhancement instructor.

Sleep is different. Sleep changes

People will give you plenty of advice about how to sleep “eight hours a night is ideal” or “youʼll wake refreshed if you stick to the ninety-minute sleep cycle”̶but the truth is that most of the advice is dubious. Sleep varies a lot from person to person, and thereʼs no such thing as “ideal sleep” that is the same for everyone. Children and seniors naturally have different needs for sleep, and your needs change from one day to the next depending on how youʼve spent your time on that particular day. Sleep is different and sleep changes. The first thing I want to communicate is that sleep is very flexible. By the way, people who say that they can fall asleep as soon as they hit the bed, or that they can sleep without a bed, are not necessarily good at sleeping. If anything, the ability to sleep anywhere and at any time may well be a sign of not getting enough sleep. So, what exactly is good sleep?

The truth about sleeping soundly

“Sleeping soundly” means good sleep. Rather than deep sleep, sleeping soundly means achieving a good balance between three factors - the amount of sleep, the quality of sleep, and the rhythm of sleep. Quality includes how quickly you go to sleep, and how you feel when you wake up. Rhythm is determined by your body clock, and amount is how long you sleep. These three elements interact, and when they are in balance, you wake up in the morning feeling as though youʼve had a good sleep. Of course, thatʼs a subjective judgment. Itʼs very difficult to find an objective scale that can be applied equally to everyone. And thereʼs one more thing about quality of sleep. As you get older, quality either stays level or deteriorates. Itʼs unreasonable to expect to return to the times when you were sleeping blissfully as soon as your head hit the pillow, slept soundly, and woke refreshed each the morning. But even if youʼre unable to sleep as long as you did before, that need not be a problem. People may say that eight hours is ideal, but if you usually wake up after six hours, thatʼs probably appropriate for your age and your bodyʼs current needs. As long as lack of sleep doesnʼt affect your daytime performance, thereʼs no need to worry. Amount and quality of sleep both change substantially as time goes by, and thatʼs perfectly normal.

Sleep is determined by your daytime activities

If you can understand how sleep works, producing a synergy between your surroundings and your habits, you can find the way of sleeping soundly that suits you best. Sleep involves two mechanisms. One is your body clock, which controls your sleep rhythm and factors such as raising and lowering your body temperature. It works to a roughly 24-hour cycle, although it is influenced by light, meal timing, and exercise. The second mechanism is the need for sleep that accumulates over the course of the day. That depends on how long you have been awake, and on what you did while you were awake. Itʼs a little like a system of points for sleep, and it resembles your appetite for food. When youʼve not moved around much, you donʼt feel particularly hungry. Similarly, the extent of your sleep drive depends on how you spent your day. Sleep always comes as a set, linked with daytime activities. The time you got up, how much sunlight you got, the changes in your body temperature, timing of meals, how much work you did, whether you had a bath, etc. Adjusting the amount of activity without disturbing your body clock, combined with occasional relaxation, allows you to manipulate your sleep. This is an example of creating your own sleep. If you pass your time sensibly during the day (see p.08 onwards), you can probably approach closer to the ideal sleep.

Sleep is how you live

So, if you accumulate a need for sleep and put your body into shape during the day, does that guarantee you a good sleep? Unfortunately not. Thereʼs another important factor: the environment or surroundings. The feel of the bedding in contact with your skin, how dark your bedroom is, your home as a whole and the way you are living all influence your sleep. How you spend your day, and in a broader sense, the environment for your sleep, act together to determine how you sleep on that particular day. There is no such thing as a correct way to sleep, but there is definitely correct knowledge about sleep. If you understand the mechanisms of sleep, then you can think about concerns, discover what is disturbing your sleep, and work out what to do to sleep better. Thinking about sleep means thinking about how you live. Rather than fixing just your bedroom or taking care just in the evening, reexamine how you live as a whole. What seems like a detour may eventually lead to a big improvement in your sleep.

Enjoy your sleep

Weʼve been focusing on the serious aspects, but fundamentally, this is about actively enjoying your sleep. Remember I described sleep as being like food. When the temperature is high, you may feel like eating a curry, some slightly sour Asian cuisine, or some other food from a hot country. Sleep works in a similar way. On a hot midsummer night, itʼs a good idea to try bedding that incorporates the wisdom of a hot country, or to leave your bed and make a place to sleep on a cool floor. Then, in winter, the wisdom of cold countries can help to keep your surroundings warm and cozy. Itʼs fun to try out ideas from people around the world to make your sleep time more enjoyable. In Japan, itʼs easy to sleep in spring and autumn, but in summer and winter the outside air temperature can get in the way. Sleep is closely connected with temperature, so itʼs only natural to change the way you sleep from season to season and in response to changes in temperature.

Itʼs OK to be free

Sleep changes under environmental influences, so itʼs not at all unusual for the same person to experience variations. On the contrary, if anyone is under the impression that he or she must sleep the same way each day, then Iʼd like to free them from that misconception. You donʼt need to worry. There are all sorts of elements and influences involved in sleep, so itʼs fine if the way you sleep changes when variations occur. In fact, itʼs probably better to think that change is normal. If your environment is completely different in summer and winter, then change is natural, just as your body changes as you get older. Itʼs better to accept change, and free yourself from any pressure you feel to achieve a regular sleep pattern.

Sleep is like making soup

Discussing sleep with a group of people, we came up with the idea that sleep is like making soup. Even if you have a recipe, ingredients, and a procedure for making the soup that fit a standard pattern, the results all taste different when different people make the soup. There are times when it turns out really well, and other times when it doesnʼt work out. Even if the ingredients are identical, the taste depends on how long you cook it for. You could put in too much salt, and thereʼs a risk that you may ruin the soup in the final stages by accidentally putting in sugar instead of salt. The trigger for this discussion was going with friends to stay at a thalasso spa. After a day of relaxing treatment, I was looking forward to a pleasant nightʼs sleep, but the night was ruined by a too-high pillow that gave me an aching neck. In the morning, I bemoaned the fact that I had been so relaxed, but it was spoiled right at the end. That was just like putting sugar in the soup. Thinking along the same lines, I realized that whether someone finds soup good or bad depends on that personʼs individual tastes. When two people try the same soup, itʼs quite possible that one will find it bland and tasteless, while the other finds it too salty. Flavor is different and flavor changes. If you think of flavor as being similar to sleep or to how soundly you sleep, you see that the relationship is complex, and it all changes according to how you spend the day. There are always going to be times when the recipe doesnʼt turn out as expected. Whether sleep is good is something that only each individual can decide. Sleep is that sort of thing.