Document Detail

Circadian and wake-dependent effects on the pupil light reflex in response to narrow-bandwidth light pulses.
MedLine Citation:
PMID:  22669721     Owner:  NLM     Status:  MEDLINE    
PURPOSE: Nonvisual light-dependent functions in humans are conveyed mainly by intrinsically photosensitive retinal ganglion cells, which express melanopsin as photopigment. We aimed to identify the effects of circadian phase and sleepiness across 24 hours on various aspects of the pupil response to light stimulation.
METHODS: We tested 10 healthy adults hourly in two 12-hour sessions covering a 24-hour period. Pupil responses to narrow bandwidth red (635 ± 18 nm) and blue (463 ± 24 nm) light (duration of 1 and 30 seconds) at equal photon fluxes were recorded, and correlated with salivary melatonin concentrations at the same circadian phases and to subjective sleepiness ratings. The magnitude of pupil constriction was determined from minimal pupil size. The post-stimulus pupil response was assessed from the pupil size at 6 seconds following light offset, the area within the redilation curve, and the exponential rate of redilation.
RESULTS: Among the measured parameters, the pupil size 6 seconds after light offset correlated with melatonin concentrations (P < 0.05) and showed a significant modulation over 24 hours with maximal values after the nocturnal peak of melatonin secretion. In contrast, the post-stimulus pupil response following red light stimulation correlated with subjective sleepiness (P < 0.05) without significant changes over 24 hours.
CONCLUSIONS: The post-stimulus pupil response to blue light as a marker of intrinsic melanopsin activity demonstrated a circadian modulation. In contrast, the effect of sleepiness was more apparent in the cone contribution to the pupil response. Thus, pupillary responsiveness to light is under influence of the endogenous circadian clock and subjective sleepiness.
Mirjam Münch; Lorette Léon; Sylvain V Crippa; Aki Kawasaki
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-07-03
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  53     ISSN:  1552-5783     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  2012 Jul 
Date Detail:
Created Date:  2012-07-04     Completed Date:  2012-10-16     Revised Date:  2013-01-09    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4546-55     Citation Subset:  IM    
Solar Energy and Building Physics Laboratory, ENAC, Swiss Federal Institute of Technology, Lausanne, Switzerland.
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MeSH Terms
Circadian Rhythm / physiology*
Melatonin / metabolism
Pupil / radiation effects*
Reflex, Pupillary / physiology*
Retinal Ganglion Cells / physiology,  radiation effects
Rod Opsins / metabolism
Saliva / metabolism
Sleep / physiology
Young Adult
Reg. No./Substance:
0/Rod Opsins; 0/melanopsin; 73-31-4/Melatonin

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