Mechanism of circadian rhythms by light and physical exercise

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K01723
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Sports science
• Research Institution: Hokkaido University
• Principal Investigator: Yamanaka Yujiro 北海道大学, 教育学研究院, 准教授 (20528343)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 生物時計 / メラトニン / 生体リズム

Outline of Final Research Achievements

The purpose of present study was to demonstrate the alternative mechanism for circadian clock regulation by exercise under bright light condition.　In this study, we examined whether exercise under bright light condition increased melatonin suppression rate as compared to bright light alone. Healthy adult subjects performed a 40-min exercise at two different intensities (low-intensity exercise, high-intensity exercise) under bright light condition at night. As a result, nocturnal melatonin concentration was not significantly suppressed by 60-min exposure of bright light alone as compared to dim light. When the subjects performed low- and high-intensity exercise under bright light, the melatonin concentrations were significantly lower than that at the dim light. However, the melatonin suppression rate did not differ between the two exercise intensities. The present findings suggest that exercise may increase the direct effect of bright light on the human circadian pacemaker.

Free Research Field

時間生物学

Academic Significance and Societal Importance of the Research Achievements

ヒトの行動および生理機能には24時間で変動する生体リズムがあり、脳内の生物時計によって発振・制御されている。生物時計は主に高照度光によって調整されるが、高照度光と運動を組み合わせることで生体リズムを効率よく調節できることが報告されている。本研究の成果は、運動の生物時計に対する作用は光の感受性を増強させることで光による生物時計の調節を促進する可能性を示し、光を十分に得られない宇宙ステーションや極端な光環境下での生体リズムを整えるために運動が有効な手段となる可能性を示した。また、夜間に運動を行う際には光環境を考慮することが生体リズムの乱れ、その後の睡眠の質を維持するうえで重要であることを示した。