Tokyo - Waseda University researchers have revealed how stress can disrupt the body's internal clock.

Our bodies have biological clocks that help maintain equilibrium of their various physiological functions. Disruption of this cycle (circadian rhythm or biological rhythm) is said to increase the risk of obesity, diabetes and cancer. Prior to this research, it was known that stress hormones affect circadian rhythm, but not how.

In experiments using mice, researchers found that stress in the hours just before sleeping has a particularly large effect on biological rhythm, much more than in the early period after waking. Furthermore, they showed that stress can disrupt the functional rhythm of the brain and other organs even more than light, but also that the body can build up resistance to the effects.

These findings suggest that psychological stress magnifies the biological rhythm impacts of night-shift work, that negative impacts can be reduced by scheduling stressful activities early in the day, and that exercise can help build tolerance to stress.

The research team was led by Professor Shigenobu Shibata (Graduate School of Advanced Science and Engineering) and Assistant Professor Yu Tahara (Institute for Advanced Study), supported by funding from the Japan Society for the Promotion of Science and assistance from the Public Health Research Foundation.

Research results are published in the online science journal, "Scientific Reports," by Britain's Nature Publishing Group.

Entrainment of the mouse circadian clock by sub-acute physical and psychological stress

About Waseda University

Waseda University is a leading institution in Japan, founded in 1882 on three principles: academic independence, practical innovation, and building an enlightened citizenship, to provide progressive leadership for the world.

Waseda has stayed true to these ideals, educating seven prime ministers and countless other politicians, business leaders, journalists, diplomats, scholars, scientists, inventors, actors, writers and artists.

Waseda's history and tradition is to tirelessly challenge convention, in favor of progress and innovation. By its 150th anniversary in 2032, the University has committed to expanding its leadership in Asia and around the world, as outlined in the Vision 150 plan.

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