Kumpei Tokuyama

Affiliation:International Institute for Integrative Sleep Medicine, University of Tsukuba

Research Title

Human sleep

Research on energy metabolism during sleep

01 Research Summary

 We measure 24-hour energy metabolism of human subjects using the human calorimeter. Last 15 years of our efforts revealed that 1) rate of substrate oxidation and energy expenditure differ between sleep stages, 2) the time course of sleeping metabolic rate is not simply the result of prolonged fasting. Energy expenditure and carbohydrate oxidation begin to increase prior to awakening despite a prolonged fasting, 3) time course of sleeping metabolism differ between male and female, suggesting that circadian clock of female during sleep is 1-2 h advanced compared to males.

 Recent findings show that control mechanisms of energy metabolism and sleep are closely related. We believe that it is important to consider the relationship between sleep and metabolism when evaluating the effects of dieting or new sleeping pills.


02 Major achievements

Tokuyama,K., Ogata H, Katayose Y, Satoh M. Algorithm for transient response of whole body indirect calorimeter: deconvolution with a regularization parameter. J Appl Physiol 106: 640–650, 2009.

Iwayama K, Kawabuchi R, Park I, Kurihara R, Kobayashi M, Hibi M, Oishi S, Yasunaga K, Ogata H, Nabekura Y, Tokuyama K. Transient energy deficit induced by exercise increases 24-h fat oxidation in young trained men. J Appl Physiol. 118:80-85, 2015.

Kayaba M, Park I, Iwayama K, Seya Y, Ogata H, Yajima K, Satoh M, Tokuyama K. Energy metabolism differs between sleep stages and begins to increase prior to awakening. Metabolism 69:14–23, 2017.

03 Education/Academic background

1983 Ehime University School of Medicine (Ph.D. in Medicine)
1983-1984 Postdoctoral Fellow at University of Southern California
1984-1986 Postdoctoral Fellow at Ottawa University
1986-1988 Postdoctoral Fellow at Swarthmore College
1988-1992 Associate Professor, Osaka Shoin Womens’ College
1992-1997 Lecturer, University of Tsukuba
1997-2007 Associate Professor, University of Tsukuba
2007-present Professor, University of Tsukuba


Why did you become a scientist?

What do you think about why people get absorbed in sports? For the same reason I devoted myself to research.

I enjoy my research just like sports. Research is very similar to sports in that many of activities are composed of collaborative work and supported by teamwork. Conducting research on human subjects, we strongly feel that we are directly contributing to human health.

What are the characteristics of your lab?

Human calorimeter

It is a whole room indirect calorimetry, which is a small airtight chamber for energy metabolism measurement. Our facility, which was installed in 2003, is currently the best in the world in time resolution with high accuracy mass spectrometer and our original noise reduction algorithm. We believe that it can be the standard specification for research facilities not only in Japan and China but also all over the world.

What are you most interested in lately?

Traveling in Southeast Asia

I have been traveling to Asian countries on business trips for several years. Lively Asian cities, where people who have similar face to us and use completely different letters live, remind me of former atmosphere in Japan. A wide variety of Asian food is also attractive to me.