Nightmare disorder in light of neuropsychological and
polysomnographic investigations
Péter Simor
Budapest University of
Technology and Economics,
Department of Cognitive
Sciences
Nightmare disorder
• Intense, disturbing mental experiences that often awaken the
dreamer (from REM or late night NREM sleep)
• Weekly basis
• Detailed, vivid recall of the emotionally negative dream
experience
• Alertness is full immediately on awakening, with little confusion or
disorientation
• The dream experience causes clinically significant distress or
impairment in social, occupational, or other important domains
DSM-IV-TR, 2000; ICSD-II, 2005
Prevalence
• Epidemiology (2-6%)
• Adults vs Children (4 % vs. 30%)
• Nightmares across the lifespan
Nielsen & Zadra (2010)
PTSD vs. Idiopathic Nightmares
Nightmare topics:
• Falling
• Being chased
• Paralyzed
• Threatening sorroundings
• Death of close persons
• Being attacked physically
• Unable to complete a task
• Accident
• Threatening animals
• Natural disasters
Schredl (2010)
Secondary symptom or Core Sleep Disorder?
•
Psychiatric perspective

Co-morbidity with
mental complaints







PTSD
BPD
Depression
Anxiety
Schizotipy
Dissociation
Suicide
Tendencies
• Sleep Medicine Perspective
 Co-morbidity is not
evident if we examine
mental complaints
among a group of
nightmare sufferers
instead of the other
way around
 Mediating factors
 Nightmare distress
 Personality
Spoormaker et al. (2006, 2008)
Independence of nightmares from mental
complaints
• PTSD: nightmares persist after the remission of waking
symptoms (Montgomery et al, 2005)
• Dream Logs: occurence of nightmares is not related to daily
variations of anxiety symptoms (Wood et al, 1990)
• Genetic studies: The high genetic heritability of nightmares
is independent of the heritability of anxiety symptoms
(Coolidge et al, 2010)
Personality
 Day-dreaming, imagination, creativity
 Neuroticism, emotional vulnerability
 Opennes to experience
 Difficulty in separating the content of different mental
states
(past-present, reality-fantasy, self and the other, etc.)
 Increased dream recall
 More complex, bizarre,
intense dreams
 Nightmares
 Lucid dreams
Levin&Nielsen, 2007
Emotional regulation and sleep
1. Emotional decoupling
2. Neural reorganization of emotional
memory representations
Walker, 2009
1. Amigdalar over-reactivity
2. Inefficient prefrontal
inhibitory control
3. Failure in emotional
regulation, emotional memory
organization
4. Dysphoric dreaming
4.
Levin & Nielsen, 2007
Behavioural studies
• Selection of participants:
• (35 NM, 35 matched CO sujects)
• Questionnaires:
• GSQS – Subjective Sleep Quality (Simor et al, 2009)
• Anxiety – STAI-T (Spielberger, 1970)
• Neuropsychological testing:
• Emotional Go/noGO task
• Emotional (verbal) Stroop task
failure
coffe
death
glass
miserable telephone
• Verbal Fluency Task
accident
umbrella
killer
seller
Go/no GO task: neutral targets and
emotional distractors
Group: F = 4,3 p = 0,04
Valence: F = 4,4 p = 0,04
BUT: the group effect is mediated
by levels of anxiety (STAI-T
scores)
NM
CO
Simor et al. (2012) Brain and Cognition
Emotional Stroop task (mixed
design)
Group effect was independent
of the effect of STAI-T and Sleep
Quality
Simor et al. (2012) Brain and Cognition
Study 2. Block design Stroop task and
classical (color-word) stroop task (19 NM,
17 CO)
- Main effect of group
- Emotional interference in both
groups
NO group difference in
either condition of the
classical color-word stroop
task
Simor et al. (2012) Brain Cogn
Verbal Fluency task
• Impaired executive functions in nightmare disorder
• Differences are not unequivocally mediated by increased anxiety levels
• Specificity?
• The role of Sleep? Causal inferences?
Simor et al. (2012) Brain Cogn
Altered sleep and nightmare frequency
• Nightmares are associated with poor subjective sleep quality (Li
et al, 2011; Schredl, 2003)
• Higher rate of nightmares in sleep disordered (insomnia, REM
behavior disorder, Narcolepsy) patients
• Nightmares are related to the subjective severity of sleep
problems (Krakow 2006)
• Few studies investigating objctive sleep
parameters (small sample size, without
controlling the confounding factors)
17 NM and 23 CO subjects spent 2 consecutive nights
in the sleep laboratory. The sleep architecture based on the
undisturbed full-night recording of the second night was
examined.
We controlled for the effects of
STAI-T and BDI (depression) scores
on our dependent variables
Fragmented sleep in nightmare disorder
p = 0.002
p = 0.007
p = 0.018
p = 0.027
0.48
pp==0.005
STAI,
BDI-H
Imbalance of sleep promoting and
arousing influences during sleep?
Simor, Horváth et al (2012) Eur Arch Psych Clin Neurosci
Nightmare Disorder and the Cyclic Alternating Pattern (CAP)
To sleep or
not to sleep?
Parrino et al, 2012
CAP A subtypes
A1 (delta 0.25-4 Hz)
A3 (alpha, 8-12 Hz)
• sleep protecting mechanism
• preparation for awakening
• related to off-line information
processing
• open state towards the
environment
• related to increased waking
executive functions (prefrontal
cortex)
• related to decreased waking
executive functions (prefrontal
cortex)
CAP A2 (mixture of fast and slow activations)
Delta activity
Alpha activity
• mixture of sleep preserving and arousing
mechanisms
• related to decreased waking executive functions
Imbalance of sleep promoting and arousing
influences
Simor et al. (2013) SLEEP
And what about REM sleep?
NS
Increased arousal processes are
only evident in NREM sleep
Arousals in REM sleep did
not differ
Limits of visual scoring?
Relative spectral power analyses (19 NM, 21 CO)
NREM, REM periods
Cz electrode
7.75-9 Hz
10-14.5 Hz
Simor et al, (2013) Biol Psychol
Correlations between NREM low alpha and REM
high alpha
NIGHTMARE SUBJECTS
CONTROL SUBJECTS
R = 0.22
R = 0.78
P < 0.0001
P = 0.33
Correlation between nightmare severity and posterior
EEG (O1,O2,Pz,P3,P4) activity in REM sleep in the
nightmare group
9-13.5 Hz
frequency
frequency
REM high alpha power peaked at posterior
locations
Wake-like EEG feature?
7.4 - 8.9 Hz
9.3 -10.9 Hz
11.3 -12.8 Hz
Increased high alpha activity in NMs reflects a wake-like feature
during REM sleep
Cantero & Atienza, 2000
Coexistence of sleep-like and wake like oscillatins in the
human brain
Nobili et al (2011)
Terzano et al, (2000)
Alpha band fluctuations and sleep disruption
McKinney et al (2011)
Descending - Ascending slopes
TRANSITION TO REM SLEEP
• aminergic demodulation
• cholinergic transmission
• glutamate mediated
amygdalar
activity
• activation of brainstem and
fronto-limbic structures
Phasic arousals, sleep
disruption and wake-like
oscillations
Halász & Bódizs, 2013
PRE vs. POST REM sleep periods
PRE vs. POST REM sleep periods: alpha power
*
Condition (F(1,37) = 25.1; p < 0.00001)
Group x Condition (F(1,37) = 9.84; p = 0.003)
Increased alpha power in NMs only in
pre-REM periods
PRE vs. POST REM sleep periods: muscle tone
Condition (F(1,36) = 9.26; p < 0.004)
Group x Condition (F(1,36) = 2.77; p = 0.1)
Tendency of increased muscle activity in NMs only
in pre-REM periods
Pre vs. Post REM: cardiovascular regulation
*
Group x Condition (F(1,37) = 7.89; p = 0.008)
Decreased parasympathetic regulation in NM
Significant group differences in pre-REM periods
Summary
•
Behavioral studies: Impaired executive functions
•
Sleep macrostructure: impaired sleep continuity, frequent awakenings,
reduced SWS, increaesed REM mediated by waking affect
•
Sleep microstructure: frequent arousals of mixed and high frequency
components reflecting sleep instability
•
Spectral analyses: Wake-like alpha oscillations during REM sleep
•
Sleep disruption and wake-like oscillations appear in the transition to
REM sleep (NREM-REM), but are not evident after the end of REM periods
•
Increased motor activity in pre-REM sleep, and reduced (stateindependent) parasympathetic cardiovascular control
Alerting mechanisms and mental activity:
the intensification of dreaming
• arousals, cortical activations and
oneiric experience
Conduit et al., 1997
Chelappa, 2011
Sleep promotion vs. environmental monitoring
OFF-LINE MODE
Marshall & Born, 2007
ON-LINE MODE
Back to psychology and to the land of speculations
• Arousals, wake-like oscillations – perceptually vivid, intense, real-like
imagery, increased dream recall
• Thin boundaries – absorption in dream images, fusion of dream and
reality
• Negative emotionality and inefficient emotional regulation –
activation of fear-related memories, environmental threats
• Alert non-restorative sleep
Acknowledgements
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Róbert Bódizs
Ferenc Gombos
Klára Horváth
János Körmendi
Ferri Raffaele
Péter P. Ujma
Klára Várhelyi
This research was supported by the
European Union and the State of Hungary,
co-financed by the European Social Fund
in the framework of TÁMOP 4.2.4. A/1-11-12012-0001 ‘National Excellence Program’.