The Japan News by The Yomiuri Shimbun

Home > Opinion > Science



Sleep and Developmental Disabilities during Adolescence

Sunao Uchida
Professor, Faculty of Sport Sciences, Waseda University

I have taught at the Faculty of Sport Sciences since 2003, and because I am psychiatrist, not only have I dedicated myself to educating students but I have also looked after the students’ mental health. As a researcher, I specialize in sleep science and take interest in sleep of students. Additionally, I have taught the medical science of sleep and “Mystery of Sleep,” the English version of the former course, at the Global Education Center. Through such interactions with students, I examined many aspects of sleep of students aged 18 to 22 (to about 27 in the case of graduate students), when most people spend time as university students. This is a summary of my analysis on this study.

The student life survey conducted by Waseda University asks students about their sleeping hours. Among recent surveys, data from the 2012 (9,481 students) and 2015 (3,217 students) show how much sleep students are getting. Figure 1, created using these data, indicates that Waseda students are estimated to have slept between six to seven hours, an amount of sleep I feel is not sufficient. University students need to sleep around eight hours so that they remain fully awake and focused during the day time.

Figure 1: Amount of Sleep by Waseda Students (%) from the Student Life Surveys

According to a survey carried out by NHK, every five years since 1960, on how much Japanese people sleep, the amount of sleep for people in their 20s on weekdays is seven hours and 27 minutes for men and seven hours and 18 minutes for women. Waseda students sleep less than average Japanese people, inferring that this lowers the quality of their lives during the daytime. They can live with these hours of sleep, but they cannot fully exert their inherent capabilities.

I understand well that this is true since I teach at the Faculty of Sport Sciences. In sports, whether an athlete is able to exert his or her abilities can easily be expressed in numbers. A study of basketball players at Stanford University shows that when they are well rested, their athletic performance continued improving over one and a half months or more. Athletic performance even improves for measure items related to the nervous system requiring accuracy, such as free throws. It could be said that the same applies to capabilities related to the central nervous system.

Taking these into consideration, it is crucial for university students to get enough sleep in order to have a fulfilling student life during the daytime. Since 1960, when NHK’s survey began, a constant decrease among Japanese people had been observed, but one recent favorable trend is that this decrease has stopped in recent years. There are two views on this trend. One is that on average, Japanese have cut down on their sleep to the point where they cannot do so any longer. Another is that various kinds of information on the importance of sleep has been provided recently, creating a keener awareness on sleep among Japanese. Nonetheless, studies such as OECD (Organisation for Economic Co-operation and Development)'s well-known survey indicate that the average number of hours Japanese spend on sleep is the shortest among OECD countries, together with South Koreans. It is desirable that the amount of sleep should be increased among university students as well as Japanese people as a whole. To that end, it is important to not only disseminate knowledge on sleep but also improve the social structure for the working population.

Figure 2: Symbols in parentheses indicate neurotransmitters produced in the nerve cells of the brain stem. Of these neurotransmitters, dopamine (DA) and noradrenalin (NE) are believed to be related to ADHD. (Gotter et al. 2012, Pharmacol Rev)

Recently, another topic has been raised about sleep problems from a psychiatric point of view. It is related to developmental disabilities. There are three major development disabilities: attention deficit hyperactivity disorder (ADHD), which is characterized by carelessness, hyperactivity, and drive impulse; autism spectrum disorder, which includes symptoms of social and communication disorder and paying peculiar attention to things; and specific learning disorder, in which patients have difficulty learning particular subjects though they do not generally suffer from intellectual development.

Among the three, ADHD has recently seen therapeutic agents develop, and in most cases, the lives of ADHD patients can considerably be improved through medication. These drugs are effective in enhancing the action of dopamine and adrenalin in the brain. As shown in Figure 2, dopamine- (DA) and noradrenalin- (NE) producing cells are located in the brain stem (the part of the brain close to the cerebrospinal cord where biological functions are concentrated). From there, fibers are sent to the cerebral cortex (the part of the brain that is responsible for thinking, judging and feeling). It is believed symptoms such as lack of attention occur because these functions weaken. On the other hand, these nerves are also related to being awake. Therefore, it is thought that if these nerves are less active, we may become sleepier, a mechanism shared by both ADHD and sleepiness.

It is not to say that all students who fall asleep during class fall into this category, but there are junior high school students or older who are overcome by sleepiness and cannot stay fully awake during the day, even though they feel the need to stay awake and study hard. This excessive daytime sleepiness hinders learning; at the same time, these students are sometimes characterized by careless mistakes lost property, loss of their belongings, and forgetfulness.

Many of these cases may be less hyperactive or impulsive, suffering from inattentive-type ADHD (or attention deficit disorder). Their lives can greatly be improved through medical treatment. In some cases I experienced, students were overcome by sleepiness so strong that during the day time, they could only remain awake for the first ten minutes of class despite their efforts. Another characteristic is that many of them feel less sleepy when they are proactively engaged in activities that interest them.

Those who lack sleep and feel sleepy only during the daytime need to get enough sleep, and it is important to improve their lifestyle by doing so. But if the symptoms described above apply to you, you are strongly recommended to consult a specialist.

In conclusion, it is most important for students to get sufficient sleep so that they can exert their inherent brain power. This is crucial to have a fulfilling life as a university student. However, if they still feel sleepy during the daytime, they are strongly recommended to consult with a specialist because a curable disease may lie behind such sleepiness.

Sunao Uchida
Professor, Faculty of Sport Sciences, Waseda University

Field of expertise
Medical science of sleep, psychiatry, cognitive science, sleep rhythm and biorhythms

Research area and research guidance at graduate school
Research in sport medicine and research guidance in sport neurology and psychiatry

Japanese Society of Psychiatry and Neurology, the Japanese Society of Sleep Research, the Japanese Association of Sports Psychiatry, and the Japanese Society of Clinical Sports Medicine