Light environment suitable for our daily activities

2009 Fiscal Year Final Research Report

• Project/Area Number: 20770200
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Single-year Grants
• Research Field: Applied anthropology
• Research Institution: Kyoto University
• Principal Investigator: TAKASU Nana Kyoto University, 医学研究科, 研究員 (30467394)
• Project Period (FY): 2008 – 2009
• Keywords: 光環境 / 生体リズム / 睡眠

Research Abstract

Circadian rhythms observed in all psychophysiological functions are produced by the circadian clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus. Intrinsically, the SCN oscillates with slightly longer than 24 hr, but generally, repeated bright light exposures at 24-hr intervals entrain the endogenous period. However, recently, irregular sleep-wake habits have been established among young people, which have disrupted the light-dark cycle. Furthermore, the number of people who are suffering from psychophysiological disorder is increasing. Therefore, we aimed at clarifying relations between the habitual sleep-wake habits and daytime psychophysiological states. In results, we demonstrated that daytime psychophysiological functions were deteriorated when the irregularity of sleep-wake rhythm was exceeded more than 3-4 hours. However, the deteriorated psychophysiological functions were recovered when irregular sleep-wake rhythm was regularized for 6 days. The present findings suggested that the regularization of sleep-wake schedule could modulate the daytime psychophysiological functions in such a way as is more adaptive to the daytime activity.