NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Human circadian pacemaker is sensitive to light throughout subjective day without evidence of transientsFifty-six resetting trials were conducted across the subjective day in 43 young men using a three-cycle bright-light (approximately 10,000 lx). The phase-response curve (PRC) to these trials was assessed for the presence of a "dead zone" of photic insensitivity and was compared with another three-cycle PRC that had used a background of approximately 150 lx. To assess possible transients after the light stimulus, the trials were divided into 43 steady-state trials, which occurred after several baseline days, and 13 consecutive trials, which occurred immediately after a previous resetting trial. We found that 1) bright light induces phase shifts throughout subjective day with no apparent dead zone; 2) there is no evidence of transients in constant routine assessments of the fitted temperature minimum 1-2 days after completion of the resetting stimulus; and 3) the timing of background room light modulates the resetting response to bright light. These data indicate that the human circadian pacemaker is sensitive to light at virtually all circadian phases, implying that the entire 24-h pattern of light exposure contributes to entrainment.
Document ID
20040172837
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Jewett, M. E.
(Harvard University Cambridge, Massachusetts 02138, United States)
Rimmer, D. W.
Duffy, J. F.
Klerman, E. B.
Kronauer, R. E.
Czeisler, C. A.
Date Acquired
August 22, 2013
Publication Date
November 1, 1997
Publication Information
Publication: The American journal of physiology
Volume: 273
Issue: 5 Pt 2
ISSN: 0002-9513
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: RO1-MH-45130
CONTRACT_GRANT: PO1-AG-09975
CONTRACT_GRANT: RO1-AG-06072
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Regulatory Physiology
Non-NASA Center

Available Downloads

There are no available downloads for this record.
No Preview Available