Document Detail

Phase-shifting Response to Light in Older Adults.
MedLine Citation:
PMID:  24144880     Owner:  NLM     Status:  Publisher    
Age-related changes in circadian rhythms may contribute to the sleep disruption observed in older adults. A reduction of the responsiveness to photic stimuli in the circadian timing system has been hypothesized as a possible reason for the advanced circadian phase in older adults. This project compared the phase shifting response to 2hours of broad spectrum white light at moderate and high intensity in young and older adults. The subjects included 29 healthy young (25.1 ± 4.1 years, M:F=8:21) and 16 healthy older subjects (66.5 ± 6.0 years, M:F=5:11) who participated in two 4-night / 3-day laboratory stays, separated by at least 3 weeks. Subjects were randomly assigned to one of three different time points 8hr before (-8), 3hr before (-3), or 3hr after (+3) the core body temperature minimum (CBTmin) measured on the baseline night. For each condition subjects were exposed in a randomized order to 2h light pulses of 2 intensities (2,000 and 8,000lux) during the 2 different laboratory stays. The phase shifts were analyzed by the time of melatonin midpoint on the nights before and after the light exposure. Older subjects in this study showed an earlier baseline phase and lower amplitude of the melatonin rhythm compared to young subjects, but there was no evidence of age-related changes in the magnitude or the direction of phase shifts of melatonin midpoint in response to 2hr of light at either 2,000 or 8,000 lux. These results indicate that the acute phase-shifting response to moderate or high intensity light is not significantly affected by age.
Seong Jae Kim; Susan Benloucif; Kathryn Jean Reid; Sandra Weintraub; Nancy Kennedy; Lisa F Wolfe; Phyllis C Zee
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-10-21
Journal Detail:
Title:  The Journal of physiology     Volume:  -     ISSN:  1469-7793     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2013 Oct 
Date Detail:
Created Date:  2013-10-22     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Northwestern university, United States;
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