Hokkaido University Research Profiles

Life Sciences

Basic Research to Design Healthy Life Rhythms Considering Biological Clocks

Yujiro Yamanaka Associate Professor
Ph.D. in Medicine

Japanese people sleep less than the global average, and the economic loss due to sleep disorders is estimated to be about 6 trillion yen per year. At our laboratory we specialize in chronobiology, which is the study of the biological clock, which is deeply related to sleep. Our goal is to contribute to the health of the nation by promoting research of chronobiology.

Content of research

The biological clock is an important biological strategy that regulates our behavior (timing of sleep and wakefulness) and our body’s internal environment, so that we can be fully active during the day and get good sleep at night. However, in today's society, many of us are forced to live against our biological clocks due to night shifts, jet lag, 24-hour work schedules, and so on. In order to lead a healthy life throughout our lives, we need to understand the structure and function of our biological clocks, and actively design and optimize our life rhythms according to our life stages and individual lifestyles. At our laboratory, we are studying the mechanism of the effects of light and exercise on the biological clock, the development of effective nutritional dietary guidance methods based on chrono-nutrition, and the relationship between seasonal variations in sleep and biological rhythms and physiological functions.

  • Research vision of our laboratory: To regulate the biological clock and lead a healthy life, it is important to regulate three clocks, namely, (1) our innate biological clock, (2) the environmental clock that controls sunlight as an environmental factor regulating the biological clock, and (3) the social clock defining our daily rhythm. However, when we look at our society, we find that many of us live lives that are against our biological clocks, and we need support to maintain our internal synchronization.

Potential for social implementation

  • ・Proposals for a suitable living environment for sleep
  • ・Proposals for countermeasures to eliminate jet lag as soon as possible
  • ・Proposals for methods to adjust sleep and biological rhythms for night shift and shift workers.
  • ・Proposals for dietary guidance based on chrono-nutrition
  • ・Proposals for methods to adjust sleep and biological rhythms according to the seasons.
  • ・Stress management and mental health considering each person's biological rhythm

Appealing points to industry and local governments

The biological clock plays an important role in maintaining the health of our mind and body. However, in today's society, there are many people who are forced to live against their biological clocks, such as those who work in shifts or go on overseas business trips. Through chronobiology research, staff at our laboratory aim to support the proposals for healthy living and working environments that take individual differences in biological clocks into account.