SLEEP 2011 Abstract Supplement

A. Basic Science III. Ontogeny/Aging
0072
AGING AFFECTS THE IMPACT OF LIGHT ON NON-VISUAL
COGNITIVE BRAIN FUNCTIONS
Vandewalle G 1,2 , Daneault V 1,2 , Hébert M 3 , Doyon J 1,4 , Dumont M 2 ,
Carrier J 1,2,4
1
Functional Neuroimaging Unit, University of Montréal, Montreal, QC,
Canada, 2 Center for Advanced Research in Sleep Medicine, University
of Montreal, Montreal, QC, Canada, 3 Centre de recherche Université
Laval Robert-Giffard, Laval University, Quebec, QC, Canada, 4 Centre
de recherche en neuropsychologie et en cognition, University of
Montreal, Montreal, QC, Canada
Introduction: Age-related change in non-visual cerebral light sensitivity
may underlie modifications in sleep-wake cycle and circadian
rhythms. Here, we investigated the acute impact of blue light exposure
on non-visual cognitive brain activity as a function of age.
Methods: 16 young (22.8 ± 4 y.o.) and 14 older (60.9 ± 4.5 y.o.) individuals
were alternatively maintained in complete darkness or exposed
to short (45s) monochromatic blue (480nm) illuminations of three irradiance
levels while performing an auditory working memory task in
fMRI. Blue light irradiance levels were 7x10^12, 3x10^13 and 10^14
photons/cm^2/s and pupil constriction was not inhibited. Data acquisition
took place 1h after habitual sleep time. Data were normalized using
state of the art techniques (Dartel in SPM8) to take into account morphological
changes with age.
Results: Performance to the task was equally high in both age groups
(> 87%), was not significantly difference between light conditions, and
showed no significant age x light intensity interaction (p > 0.05), preventing
behavioural bias of fMRI results. fMRI analyses revealed that,
taking into account age-related differences in brain activity independent
of the light condition, increasing irradiance enhanced brain responses to
the task more strongly in younger than older individuals (p corrected <
0.05). These age-related differences in the impact of light irradiance on
brain responses to the task were found in the thalamus, prefrontal cortex,
hippocampus, and cerebellum.
Conclusion: These results show that the stimulating effect of blue light
on non-visual cognitive brain function decreases with age in regions
important for cognition (prefrontal cortex, hippocampus, thalamus) and
alertness regulation (thalamus). Future research will determine if this
decrease reflects age-related changes at the level of the brain, of the eye,
or both.
Support (If Any): IRSC, CRSNG, FRSQ
0073
OBJECTIVE SLEEP BY AGE AND SEX IN A LARGE AT-
HOME SAMPLE
Fabregas SE
Sleep Research Center, Zeo, Inc, Newton, MA, USA
Introduction: It may be concluded from previous research that objective
sleep quality depends, in part, on both age and biological sex.
However, there is very little information available about the interacting
effects of age and sex on sleep. This is especially true of objective measures
of sleep taken in home settings.
Methods: The DOZER sleep registry is an IRB approved database of
de-identified, objectively measured sleep (via the Zeo) in the home. Participants
use the instrument and upload data to the registry as they see fit.
Measures include Total Sleep Time (TST), Time in REM (REM), Time
in Light (Light, stages 1 and 2), and Time in Deep (Deep, stages 3 and
4). Age groups were categorized by decade and sleep measures were
averaged for each subject who contributed more than one night of data.
Two-way factorial ANOVAs were run to look for the effects of age and
sex on these measures. An alpha level of 0.001 was set to account for the
large sample size and the number of tests run in the analysis.
Results: 7,473 subjects (ages 17-89, 25% female) contributed 298,500
nights of data for analysis. A significant (p