| Time-dependent effects of dim light at night on re-entrainment and masking of hamster activity rhythms. | |
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MedLine Citation:
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PMID: 20348461 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Bright light has been established as the most ubiquitous environmental cue that entrains circadian timing systems under natural conditions. Light equivalent in intensity to moonlight (<1 lux), however, also strongly modulates circadian function in a number of entrainment paradigms. For example, compared to completely dark nights, dim nighttime illumination accelerated re-entrainment of hamster activity rhythms to 4-hour phase advances and delays of an otherwise standard laboratory photocycle. The purpose of this study was to determine if a sensitive period existed in the night during which dim illumination had a robust influence on speed of re-entrainment. Male Siberian hamsters were either exposed to dim light throughout the night, for half of the night, or not at all. Compared to dark nights, dim illumination throughout the entire night decreased by 29% the time for the midpoint of the active phase to re-entrain to a 4-hour phase advance and by 26% for a 4-hour delay. Acceleration of advances and delays were also achieved with 5 hours of dim light per night, but effects depended on whether dim light was present in the first half, second half, or first and last quarters of the night. Both during phase shifting and steady-state entrainment, partially lit nights also produced strong positive and negative masking effects, as well as entrainment aftereffects in constant darkness. Thus, even in the presence of a strong zeitgeber, light that might be encountered under a natural nighttime sky potently modulates the circadian timing system of hamsters. |
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Authors:
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David W Frank; Jennifer A Evans; Michael R Gorman |
Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural |
Journal Detail:
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Title: Journal of biological rhythms Volume: 25 ISSN: 1552-4531 ISO Abbreviation: J. Biol. Rhythms Publication Date: 2010 Apr |
Date Detail:
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Created Date: 2010-03-29 Completed Date: 2010-06-21 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8700115 Medline TA: J Biol Rhythms Country: United States |
Other Details:
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Languages: eng Pagination: 103-12 Citation Subset: IM |
Affiliation:
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Department of Psychology, University of California, San Diego, La Jolla, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Behavior, Animal Biological Clocks Circadian Rhythm* Cricetinae Cricetulus Darkness Light Male Phodopus Photic Stimulation Photoperiod Physical Conditioning, Animal Suprachiasmatic Nucleus / metabolism* Time Factors |
| Grant Support | |
ID/Acronym/Agency:
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HD-36460/HD/NICHD NIH HHS |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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