SLEEP 2011 Abstract Supplement

A. Basic Science V. Physiology
Introduction: First night effect is a well-described phenomenon of objective
sleep disturbance associated with the stress of sleeping in the unfamiliar
environment of the sleep laboratory. The goal of this study was
to assess whether sleep variables affected by the first night are associated
with baseline cortisol secretion.
Methods: One hundred forty nine, healthy, normal sleepers (83 men,
66 women), mean age ±SD, 31.0 ±12.5, range 18.0 to 59.2 years; mean
BMI±SD 24.5 ± 2.7, range 18.3 to 30.0 participated in a 4 consecutivenight
sleep laboratory protocol [1 adaptation night, nights 2 and 3 and
the fourth night a serial 24-hour plasma blood sampling was performed ].
We tested whether the change from night 1 to the average of nights 2 and
3 of 7 key sleep variables (sleep latency, percent sleep time, wake time
after sleep onset, stage 1 minutes, stage 2 minutes, slow wave sleep minin
the dark, the delta rebound was reduced for both the ZT6 and ZT12
SD. The increase in theta power during SD was lower for the ZT12 and
ZT18 SD than for the ZT0 SD, but only the increase during ZT0 SD
appears to be blunted in the dark condition. Importantly, simulations
showed that the level of delta power during the first 10 min of recovery
sleep could not be adequately predicted for the ZT6 SD but only when
SD was performed in the light.
Conclusion: Our data suggest that sleep pressure dynamics depends
both on time-of-day and environmental light. We are currently working
on the precise estimation of the effect of these variables on sleep pressure
markers.
Support (If Any): University of Lausanne, FNS (3100A0-111974),
NSERC fellowship
0129
CHRONIC LIGHT AS A POTENTIAL REGULATOR OF SLEEP
HOMEOSTASIS
Sunagawa G, Hayashi M, Ueda HR
Laboratory for Systems Biology, Center for Developmental Biology,
Kobe, Japan
Introduction: Mammalian sleep is under control of circadian clock and
sleep homeostasis. The mechanism of circadian clock is studied intensively
although the sleep homeostasis is poorly understood. One reason
of less progress in sleep homeostasis research is the lack of method to
perturb sleep homeostasis dominantly without interacting the central
clock. In this study, we showed that chronic light can control the amount
of locomotor activity of mice both in wild-type and in arrhythmic mice.
Methods: CB57BL mice (WT) and two arrhythmic strains, cry1(-/-)
cry2(-/-) mice (CRY-DKO) and bmal1(-/-) mice (BMAL-KO) were
used in this study. Every mice were caged individually and their locomotor
activity was detected by infrared beams. In the first experiment,
mice were placed in LD=12:12 condition at least 7 days and followed
by 7 days of constant darkness (# of mice: WT n=34, CRY-DKO n=6,
BMAL-KO n=34). In the second experiment, WT (n=34) and CRY-
DKO (n=31) were divided into four groups. Two groups were caged
3 weeks in constant light or in constant dark condition as controls. The
other two groups received L-D-L or D-L-D light pattern (each letter
stands for light conditions of a week) for 3 weeks. In the ongoing third
experiment, EEG/EMG recordings were taken with these mice for two
weeks. Each strains are divided into two groups, which are constant dark
group and D-L group. Both groups were caged under constant darkness
for the first 7 days, and only in the D-L group, light was switched on in
the latter half period.
Results: In the first experiment, we found that switching mice from
LD=12:12 to constant darkness leads in stable increase of daily locomotor
activity. Interestingly, this happened not only in WT but also in
CRY-DKO and in BMAL-KO. In the second experiment, shifting mice
from constant darkness to constant light showed stable decrease in daily
locomotor activity and vice versa. The activity difference between constant
dark and light was larger in CRY-DKO than in WT.
Conclusion: Our data showed that chronic light condition is capable of
controlling daily amount of the locomotor activity in mice. Importantly,
the chronic light induced suppression of locomotor activity seems to occur
independently from the central clock. According to these facts, we
hypothesized that chronic light can control sleep homeostasis. Ongoing
experiments are examining the change in sleep under different chronic
light conditions in these mice.
0130
WHO IS VULNERABLE TO INSOMNIA? INVESTIGATING
THE ROLE OF STRESS REACTIVITY, PERONSALITY AND
COPING
Harvey C 1,2 , Holly S 2 , Beattie L 1 , Espie CA 1,2 , Biello S 1
1
University of Glasgow Sleep Centre, University of Glasgow, Glasgow,
United Kingdom, 2 School of Psychology, University of Glasgow,
Glasgow, United Kingdom
Introduction: Our understanding of the psychological and physiological
characteristics related to a trait like vulnerability to sleep disruption
is limited. The aim of the current work is to assess physiological stress
responses and psychological factors in individuals vulnerable vs. resilient
to developing insomnia. This research is the first to experimentally
characterise those who are presumed pre-disposed to insomnia.
Methods: A group of good sleepers (n=25) completed the Trier Social
Stress Test (TSST), which is known to have robust effects on both
subjective and objective measures of stress. Salivary-free cortisol was
obtained throughout the task, as an indication of stress reactivity. A ‘vulnerable’
and ‘resilient’ group were created based on responses to the
Ford Insomnia Responsivity to Stress Test (FIRST) and compared on
psychological variables (Personality, perceived stress, coping and sleep)
and physiological stress response.
Results: Preliminary results demonstrate that those above the median
split on FIRST score showed significantly higher values in neuroticism
and rumination (p< 0.05) and a trend toward emotion focused and maladaptive
coping strategies (p=0.055; p=0.08 respectively), as expected.
There were no group differences in perceived stress, sleep parameters,
depression or anxiety. While not significant, those in the ‘vulnerable’
group, on average, showed a greater peak in salivary cortisol compared
to the ‘resilient’ group. Data collection is still ongoing and we hypothesise
the change in salivary cortisol to become significant with further
data.
Conclusion: Those vulnerable to developing insomnia show differences
in personality and coping style. Data gathered to-date suggests a tendency
toward increased stress reactivity amongst this group, supporting
the idea that a trait-like vulnerability to insomnia exists, and is manifest
physiologically. This has obvious implications for our understanding of
the aetiology of insomnia.
Support (If Any): This work forms part of a Ph.D. supported by the
Sackler Institute fo Psychobiological Research.
0131
FIRST NIGHT EFFECT: ASSOCIATION OF REM SLEEP
REDUCTION WITH THE HYPOTHALAMIC-PITUITARY-
ADRENAL AXIS (HPA) ACTIVITY
Pejovic S 1 , Vgontzas AN 1 , Liao D 2 , Fernandez-Mendoza J 1 , Calhoun S 1 ,
Bixler EO 1
1
Psychiatry, Penn State College of Medicine, Hershey, PA, USA,
2
Public Health Services, Penn State College of Medicine, Hershey, PA,
USA
SLEEP, Volume 34, Abstract Supplement, 2011
A48