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Light masking of circadian rhythms of heat production, heat loss, and body temperature in squirrel monkeysWhole body heat production (HP) and heat loss (HL) were examined to determine their relative contributions to light masking of the circadian rhythm in body temperature (Tb). Squirrel monkey metabolism (n = 6) was monitored by both indirect and direct calorimetry, with telemetered measurement of body temperature and activity. Feeding was also measured. Responses to an entraining light-dark (LD) cycle (LD 12:12) and a masking LD cycle (LD 2:2) were compared. HP and HL contributed to both the daily rhythm and the masking changes in Tb. All variables showed phase-dependent masking responses. Masking transients at L or D transitions were generally greater during subjective day; however, L masking resulted in sustained elevation of Tb, HP, and HL during subjective night. Parallel, apparently compensatory, changes of HL and HP suggest action by both the circadian timing system and light masking on Tb set point. Furthermore, transient HL increases during subjective night suggest that gain change may supplement set point regulation of Tb.
Document ID
20040142087
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Robinson, E. L.
(University of California Davis, California 95616-8519, United States)
Fuller, C. A.
Date Acquired
August 22, 2013
Publication Date
February 1, 1999
Publication Information
Publication: The American journal of physiology
Volume: 276
Issue: 2 Pt 2
ISSN: 0002-9513
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Regulatory Physiology

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