Accession Number : ADA337545

Title :   Phase Shifting Effects of Light and Activity on the Human Circadian Clock

Descriptive Note : Final rept. 1 May 94-31 Oct 97

Corporate Author : CHICAGO UNIV IL

Personal Author(s) : Van Cauter, Eve

PDF Url : ADA337545

Report Date : 15 FEB 1998

Pagination or Media Count : 18

Abstract : The goals of this research are to delineate basic mechanisms controlling the human circadian clock and to derive practical procedures to rapidly phase-shift human rhythms in real life situations. The focus is on the impact of the: interactions between circadian rhythmicity and sleep-wake regulation on endocrine function, metabolism, cardiovascular function, mood and cognition. The studies are designed to approximate real life conditions and examine conditions of circadian misalignment and sleep loss that are relevant to Air Force operations. This effort demonstrated that physical exercise is capable of phase-delaying human rhythms and that daytime exposure to dark may result in rapid phase-advances. We also showed that the subjective discomfort, fatigue, and decreased performance which occur following time shifts (i.e. the "jet lag syndrome") are associated not only with a misalignment of bodily rhythms but also with a prolonged elevation of a hormonal concentration in blood. Recent studies further indicated that partial sleep loss, whether acute or chronic, results in marked alterations of endocrine and metabolic function. These observations challenge the common belief that sleep deprivation affects mood and cognition, but not peripheral physiology, and emphasize the need to develop countermeasures to minimize decrements in both mental and physical function.

Descriptors :   *CIRCADIAN RHYTHMS, *LIGHT, *JET LAG, COGNITION, SIGNS AND SYMPTOMS, METABOLISM, MENTAL ABILITY, CARDIOVASCULAR SYSTEM, MISALIGNMENT, SLEEP, FATIGUE(PHYSIOLOGY), EXERCISE(PHYSIOLOGY), ENDOCRINE GLANDS.

Subject Categories : Anatomy and Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE