Dreamlike Mentations during SleepWalking in Adults
Dreamlike Mentations During Sleepwalking and Sleep Terrors in Adults
Delphine Oudiette, MSc; Smaranda Leu, MD; Michel Pottier, MD; Marie-Annick Buzare, MD; Agnès Brion, MD; Isabelle Arnulf, MD, PhD
Sleep Disorders Unit, Pitié-Salpêtrière Hospital, APHP, UMR 975, CRICM, and Paris 6 University, Paris, France
Background: Sleep terrors and sleepwalking are described as arousals from slow wave sleep with no or poor mental recollection.
Objective: To characterize the mental content retrospectively associated with sleep terrors or sleepwalking.
Setting: University Hospital
Design: Controlled prospective cohort
Participants: Forty-three patients referred for severe sleepwalking/sleep terrors (age: 26 ± 7 y, 46% men, 5 with sleep terrors only, 8 with sleepwalking only,
and 30 with both), matched with 25 healthy control subjects.
Intervention: Thirty-eight of the 43 patients (88%) underwent an interview about the frequency, time, behaviors, and mental content associated with the episodes of sleepwalking and sleep terrors, whenever they occurred over a lifetime. The mental contents were classified for complexity (Orlinski score), and for
characters, emotions, fortune/misfortune, and social interactions (Hall and Van de Castle categories). Patients and control subjects underwent an overnight
video-polysomnogram.
Results: Seventy-one percent of the patients reported at least 1 dreamlike mentation associated with the sleepwalking/sleep terrors episode. The dreamlike
mentation action corresponded with the observed behavior. A total of 106 dreamlike mentations were collected (mean: 3 ± 3.4 dreamlike mentations/patient,
range 0-17). Most (95%) dreamlike mentations consisted of a single visual scene. These dreamlike mentations were frequently unpleasant, with aggression
in 24% (the dreamer being always the victim), misfortune in 54%, and apprehension in 84%. The patients with dream mentations reported more severe
daytime sleepiness.
Conclusion: Short, unpleasant dreamlike mentations may occur during sleepwalking/sleep terrors episodes, suggesting that a complex mental activity takes
place during slow wave sleep. Sleepwalking may thus represent acting out of the corresponding dreamlike mentation.
Keywords: Sleepwalking, sleep terror, dream
Citation: Oudiette D; Leu S; Pottier M; Buzare MA; Brion A; Arnulf I. Dreamlike mentations during sleepwalking and sleep terrors in adults. SLEEP
2009;32(12):1621-1627.
SLEEPWALKING AND SLEEP TERRORS CONSIST OF A
SERIES OF COMPLEX BEHAVIORS THAT ARE INITIAT�
ED DURING SUDDEN AROUSALS FROM SLOW WAVE
sleep (SWS). Episodes often begin with sitting up in bed and
looking about in a confused manner. Sleepwalking and sleep
terrors show considerable overlap and share many features. In�
deed, at least 1��������������������������������������������������
���������������������������������������������������
of the following is present in both of the disor�
ders: (1) difficulty arousing the person, (2) mental confusion
when awakened from an episode, (3) complete or partial amne�
sia for the episode, and (4) dangerous or potentially dangerous
behaviors during the episode.1 Both disorders arise from SWS,
frequently cooccur in the same family or patient, and have a
strong genetic background.2
In contrast with SWS, rapid eye movement (REM) sleep
has, for a long time, been considered as the neurobiologic
basis of dreaming. Nevertheless, complex mentations are re�
ported in 5% to 74% of non-rapid eye movement (NREM)
sleep awakenings.3-8 The extent to which the reported men�
tation may legitimately be described as “dreaming” is still
debated.8,9 Indeed, there are qualitative and quantitative differ�
ences between NREM- and REM-sleep dreams. NREM-sleep
dreams, especially when elicited during the first half of the
night, are usually reported as being shorter, less complex, less
vivid, and more “thought like” than REM-sleep dreams.7,10-12
NREM sleep dreams can also be a recollection of the previous
REM-sleep dreams.
Although there are sporadic descriptions of the mental con�
tent associated with sleepwalking or sleep terrors in the litera�
ture,13-18 there is a general consensus against a complex dream
activity associated with the sleepwalking/sleep terrors.19 More�
over, some authors have proposed that the sleepwalking/sleep
terrors is triggered by the physiologic changes occurring dur�
ing the arousal state (e.g., accelerated heart rate and respira�
tory changes) rather than by the mental activity preceding the
arousal state.20 In a cohort of patients with sleepwalking/sleep
terrors, we investigate whether dreamlike mentations are fre�
quent at the very moment of the episode and compare the sleep
structure and daytime sleepiness of these patients with those of
healthy matched control subjects.
METHODS
Patients
All patients with sleepwalking/sleep terrors who were moni�
tored with video-polysomnography (including an extensive
8-electroencephalographic channel montage) in our sleep dis�
order unit during the last 2 years were prospectively evaluated.
This is an adult unit with occasional investigations of children
younger than 15 years of age. The patients were referred be�
cause of severe nocturnal behaviors that were dangerous, dis�
turbing, or frequent. Patients with parasomnia overlap disorders
(when sleepwalking/sleep terrors is combined with REM sleep
behavior disorder [RBD]), nocturnal epilepsy, sleep sex, and
sleep-related eating disorder (as the exclusive symptoms) and
patients with psychosis were excluded. There were 43 patients
with sleepwalking/sleep terrors (sleepwalking only, n = 8; sleep
Submitted for publication March, 2009
Submitted in final revised form August, 2009
Accepted for publication August, 2009
Address correspondence to: Isabelle Arnulf, Unité des Pathologies du
Sommeil, Hôpital Pitié-Salpêtrière, 47-83 boulevard de l’Hôpital, 75651
Paris Cedex 13; Tel: 01 42 16 77 04; Fax: 01 42 16 77 00; E mail: isabelle.
[email protected]
SLEEP, Vol. 32, No. 12, 2009
1621
Dreamlike Mentations and Sleep Terrors in Adults—Oudiette et al
terrors only, n = 5; and both, i.e. displaying either sleep terrors
some nights, sleepwalking some other nights, or night terrors
followed by sleepwalking, n = 30). Sleepwalking was defined
as (1) a history of ambulation during sleep; (2) the persistence
of sleep or impaired judgment during ambulation; and (3) the
disturbance was not better explained by another sleep, medi�
cal, mental, neurological disorder, or medication/drug use.1
Sleep terrors were defined as (1) a history of a sudden episode
of terror occurring during sleep, usually initiated by a cry or
loud scream with sympathetic and behavior manifestations of
intense fear; (2) difficulty in arousing the person, or mental con�
fusion when awakened from an episode, or complete or partial
amnesia for the episode, or dangerous or potentially dangerous
behaviors; (3) the disturbance was not better explained by an�
other sleep, medical, mental, neurological disorder, or medica�
tion/drug use.1 In addition to these clinical criteria, we observed
in all patients at least 1����������������������������������������
�����������������������������������������
of the following features on the video�
polysomnography (although they are neither totally sensitive
nor specific, they are supportive in the context of a systematic
study): (1) at least 1������������������������������������������
�������������������������������������������
arousal during NREM sleep stage 4 associ�
ated with an abnormal motor behavior suggesting surprise, con�
fusion, or fear (startling, sitting in the bed, or looking around
surprised); (2) numerous sudden arousals during NREM sleep
stage 4; or (3) hypersynchronous delta waves before an arousal
in NREM sleep stage 4. Because sleepwalking and sleep terror
share many features, we pooled patients with sleepwalking with
those with sleep terrors in the next part of this article. Their
demographic, clinical (body mass index, Epworth Sleepiness
Scale score), and sleep characteristics during polysomnogra�
phy were compared with those from 25 age- and sex-matched
healthy controls without sleep disorders. The control subjects
were retrospectively selected from our database after they took
part in another paid study.
dreamlike mentation if the score ranged from 2 to 7. We used
the nominal categories (characters; emotions; social interac�
tions including aggression, friendliness, and sexuality; misfor�
tune and good fortune; and success and failure) of the Hall and
Van De Castle method to qualify each mental-content compo�
nent.23 We determined the presence or absence of any given cat�
egory, in accordance with the “at least 1” procedure. Because
most dreamlike mentation contents in sleepwalking/sleep ter�
rors contained fewer than 50 words, we used only the categories
of this method, but not the normative values, which have been
established for 50- 350-word dream contents. Whenever pos�
sible, family members were also interviewed. A demonstrative
case report of dreamlike mentation contents obtained during
sleepwalking/sleep terrors is presented in the Appendix.
Sleep was monitored for 1 night in all subjects using videoelectroencephalography (8 channels) in patients and 3 electro�
encephalographic channels in control subjects, and we used
classic channels (eyes movements, chin and leg electromyog�
������������
raphy, nasal pressure, body position, thoracic and abdominal
respiratory efforts, pulse oximetry, electrocardiography, and
sounds) in all participants. The sleep stages, arousals, periodic
leg movements, and respiratory events were scored using the
international criteria, as previously described.24
Statistics
Data are presented as mean ± SD, unless otherwise specified.
The comparisons between the patients and the control subjects
were performed using the student t test.
RESULTS
Clinical Characteristics of Patients with NREM Sleep Parasomnia
The 43 patients with sleepwalking/sleep terrors were aged
11 to 72 years at the time of the videopolysomnography (mean
age: 26 ± 7 years). Only 1 patient was a child, the other patients
being adult. Forty-six percent were male, with a mean body
mass index of 22.7 ± 3.4 kg/m2 (not different from controls).
Patients were 4 to 61 years old at the onset of parasomnia (mean
age: 12 ± 12). They experienced sleepwalking/sleep terrors for
20 ± 12 years. They had great difficulties estimating the fre�
quency of their episodes. Most patients said the episodes came
irregularly, with clusters for several days to weeks. The events
occurred during the first 2 hours of sleep in 88% patients. When
they occurred, there was a single event per night in 55% and
more than 1 event per night in 45%. The precipitating factors
were alcohol intake in 14%, sleep deprivation in 28%, stress
or argument in 58%, a specific context from the preceding day
(such as watching a horror film or an action-filled film or read�
ing a thriller) in 16%, sleeping at someone else’s house in 5%,
and unknown in 16%.
Investigations
All patients underwent a semistructured interview admin�
istered by a sleep specialist that included assessments of the
medical history, any family history of parasomnia, the age at
sleepwalking/sleep terrors onset, the frequency and timing of
the sleepwalking/sleep terrors episodes, and predisposing fac�
tors (such as alcohol intake, sleep deprivation, stress, or change
of room). In addition, we asked the patients about their men�
tal content during the episodes of sleepwalking or sleep terrors
using the following question: ”What was going through your
mind at the very moment of the episodes, whenever the night?”
Our data had been gathered retrospectively, so that the dream�
like mentation collection covered a lifetime span for each pa�
tient. Most patients had the greatest difficulty precisely dating
the time of the sleep terrors/sleepwalking-associated dreamlike
mentation. After obtaining the spontaneous mentation report,
we interviewed the patient more pointedly to elicit additional
information, including characters, emotions, and bizarre ele�
ments. We classified the mental contents according to their
complexity using the Orlinski score21,22 (0: No dream recall; 1:
Feeling of having dreamt but no memory of it; 2: One scene; 3:
More than 1 scene; 4: Coherent dream; 5: Coherent and detailed
dream with the dreamer as an actor; 6: Prolonged, image-filled
scenario resembling real life; 7: Prolonged, image-filled sce�
nario with bizarreness). The mental content was defined as a
SLEEP, Vol. 32, No. 12, 2009
Mental Content During Sleepwalking or Sleep Terrors
Thirty-eight out of 43 patients (88%, including 2/5 patients
with sleep terrors only, 6/8 patients with sleepwalking only, and
30/30 patients with sleep terrors and sleepwalking) could re�
liably answer questions about their mental content during the
parasomnia episodes. The mental content was classified using
the Orlinski score (Table 1). Among them, 27 of 38 (71%) re�
ported at least 1 incidence of mental content associated with
1622
Dreamlike Mentations and Sleep Terrors in Adults—Oudiette et al
an episode. Four additional patients had the feeling of hav�
ing dreamt during at least 1 episode but had no clear memory
about the dreamlike mentation. Most mental contents (95%)
were brief, corresponding with the vision of a single scene. A
single patient (a child, 11 years old) experienced a prolonged,
image-filled, and complex dreamlike mentation, with several
scenes and odd features. An example of dreamlike mentations
reported by a patient with sleepwalking and sleep terrors is
detailed in Appendix. According to the categories of the Hall
and Van de Castle method, 39% of patients described the pres�
ence of at least 1 person. The people seen during sleepwalking/
sleep terrors were mostly unknown by the dreamer (uncertain
identity: 33%, strangers: 24%), whereas only 33% were rela�
tives of the dreamer. Eleven percent of patients saw animals,
generally aggressive or frightening, during sleepwalking/sleep
terrors. A dreamlike mentation was classified as containing ag�
gression when the situation involved a deliberate intentional act
on the part of 1����������������������������������������������
�����������������������������������������������
character to harm or annoy some other charac�
ter. The classification of misfortune was used to handle those
situations in which injury, mishap, or adversity occurred to a
character through chance or environmental circumstances over
which it was impossible to exert personal control (“something
bad happens”). During sleepwalking/sleep terrors, most mental
contents (80%) were bad dreamlike mentations with aggression
(26% of the total number of dreamlike mentations) and mis�
fortune (54%). In the case of aggression dreamlike mentations,
the patient was never the first aggressor, except for one patient
who “was ordered to stab the flesh of somebody on pain of be�
ing killed.” In addition, 12% of the dreamlike mentation reports
contained at least 1 act of friendliness. In all cases, the patient
was a befriender who attempted to protect someone (generally a
relative) from danger. In contrast, no patient in a dangerous situ�
ation was befriended or rescued. There were no sexual elements
in the dreamlike mentation reports. The majority of dreamlike
mentations (84%) were negatively perceived, with apprehen�
sion, fear, or terror at the heart of them. The 4 patients with
no clear dreamlike mentation recall had only a feeling of pure
fear, with no associated images (Table 2). Seventeen patients
acted out nonaggressive behaviors such as laughing, singing a
dirty song, or saying “how nice are the bees” with no associated
dreamlike mentation recall. All patients had some additional,
more usual, “good,” and classic dreams that they would recall
the following morning.
We tried to distinguish patients with isolated sleep terrors (n
= 5), with isolated sleepwalking (n = 8), and with both phenom�
ena (n = 30). Unfortunately, only 2 of 5 patients with isolated
sleep terrors were appropriately interviewed, and only 1 of
these 2 patients remembered at least 1 mentation (2 frightening
images) associated with the sleep terrors. As for isolated sleep�
walking, 6 of 8 patients were appropriately interviewed and
only 2 of the 6 remembered at least 1 mentation associated with
the sleepwalking. These 2 patients reported 6 different menta�
tions, with 2 of 6 containing a frightening image (Supplemental
Table 1 available online at www.journalsleep.org).
Table 1—Characteristics of Mental Content Associated with Sleepwalking or Sleep Terrors
Patients
Patients with sleepwalking/sleep terrors, No.
43
Patients appropriately interviewed, No.
38
Patients with at least one mental content recall, %
71% (27 of 38)
Total number of dreamlike mentations
106
Number of dreamlike mentations per person (mean ± SD) 3.0 ± 3.6
Number of dreamlike mentations per person (range) 0-17
Type of mental content: Orlinski scale
No real mental content (% of 38 patients)
0. No dream recall
18% (7 of 38)
1. Feeling of having dreamt but no memory of it 11% (4 of 38)
Mental content recall (% of all dreams obtained)
2. Vision of one scene
95% (101 of 106)
3. Vision of more than one scene
0% (0 of 106)
4. Coherent dream
4% (4 of 106)
5. Coherent and detailed dream, with the
0%
dreamer as an actor
6. Prolonged, image-filled scenario, resembling
0%
real life
7. Prolonged, image-filled scenario, with bizarre- 1% (1 of 106)
ness
Dreamlike mentations (% of all dreams obtained) with at least one
Character
People
40% (42 of 106)
Animals
11% (12 of 106)
Social interaction
Aggression
24% (25 of 106)
Dreamer as a victim, % of aggression dreams 100% (25 of 25)
Dreamer as an aggressor, % of aggression dreams 4% (1 of 25)
Friendliness
11% (12 of 106)
Befriender, % of friendliness dreams
100% (12 of 12)
Befriended, % of friendliness dreams
0% (0 of 12)
Sexuality
0% (0 of 106)
Fortune and misfortune
Fortune
0% (0 of 106)
Misfortune
54% (57 of 106)
Emotions
Anger
2% (2 of 106)
Apprehension
84% (89 of 106)
Sadness
0% (0 of 106)
Confusion
0% (0 of 106)
Happiness
0% (0 of 106)
stages, arousal index, apnea-hypopnea index, and periodic leg
movements. The number of sudden arousals from SWS varied
from 1 to 13 in patients and 0 to 4 in control subjects. It was
4 times higher in patients than in control subjects. The sudden
arousals from SWS were not preceded by any respiratory event,
including flow limitation. The patients had an Epworth Sleepi�
ness Scale score of 10 ± 4, and 47% of them had an abnormal
sleepiness score (greater than 10). Their mean sleepiness score
was higher than in the control group, but the control subjects
were selected for having no abnormal sleepiness.
Thirty-five of the 43 (81%) patients exhibited at least 1
arousal during non-REM sleep stage 4 associated with an
Sleep Measures in Sleepwalkers and in Controls
With regard to the sleep architecture (Table 3), there was
no difference between the patient and control groups for sleep
duration and efficacy, sleep-onset latency, percentages of sleep
SLEEP, Vol. 32, No. 12, 2009
1623
Dreamlike Mentations and Sleep Terrors in Adults—Oudiette et al
Table 2—Examples of the Mental Content During Sleepwalking/Sleep Terrors and Associated Behaviors
Patient
Mental content
Patient 4, F,
34 y
Patient 4
Patient 5,
F, 32 y
Patient 7,
F, 66 y
Patient 9,
F, 27 y
Patient 14,
F, 26 y
Patient 18,
F, 32 y
Patient 18
She was going to get run over by a truck.
Patient 19,
M, 11 y
Patient 25,
F, 72 y
Patient 28,
M, 30 y
Patient 34,
M, 28 y
She plunged into death.
Behaviors (observed by a cosleeper or
by the dreamer)
She leapt out of bed and out of the mezzanine to avoid it.
She spat in her bed to drown them.
She grabbed her baby and ran out of the
room with it.
She yelled.
She was locked in a box she could not escape. She felt herself suffocating.
She pushed back the walls around her.
She broke a vial containing a lethal virus.
She shouted.
She saw Death with its dark cape and an emaciated hand coming up close to her face
and about to kill her.
She saw a crack above her bed containing dead flesh. Cockroaches crawled on the
dead flesh, then fell in her bed and hair. She rubbed her hair to remove them and saw
a cockroach drop and run on the floor
She yelled and ran away.
There were spiders.
Her baby was jeopardized.
He went to the roof of the house because people were following him and his little
brother. He forbade his brother to climb on the roof because of the danger. On the way,
he picked up luminous balls. There were also people at the bottom of the house.
The ceiling was collapsing.
He was skiing and hurtling down an icy steep slope, with a ravine at the end of the
slope. He could not stop from falling in the abyss
His girlfriend was in danger.
abnormal motor behavior suggesting surprise, confusion,
or fear (startling, sitting in the bed, or looking around sur�
prised). Most of the episodes were minor and much less im�
portant than those described at home. Because these patients
were first referred to our sleep unit for a clinical (and not a
research) purpose, they were not interviewed by the nurse just
after the brief parasomnia to collect their mentations. No pa�
tient reported any dreamlike mentation when interviewed in
the morning after the videopolysomnography night. A video
of a patient with sleep terror (opening the eyes and looking
scared before screaming) is displayed as supplemental video
available online at www.journalsleep.org. On the next morn�
ing, she did not remember any mental content. During similar
events at home, she had the vision of being locked in a box
and suffocating or being attacked by something or somebody
unknown.
She shouted, jumped out of the bed, and
pushed the wall.
He shouted and leaped out of the bed.
He pulled his girlfriend out of the bed to
save her.
This study highlights the presence of dreamlike mentation
content during an episode of sleepwalking/sleep terrors in
adults. These results are concordant with those from a study of
a group of 12 patients with sleep terrors who slept with elec�
troencephalographic and heart rate monitoring during 4 to 23
nights.18 In this group, a mean of 58% recall of mental content
was obtained after spontaneous arousals from NREM sleep as�
sociated with heart rate acceleration (but not necessarily with a
scream). Apart from this case series reported in 1974, dreamlike
mentations associated with a sleepwalking/sleep terror episode
have been described incidentally.
A young patient rushed into the room where his parents
were sitting and threw the butter dish out of the window,
believing it to be a bomb.17
A sleepwalker threw his wife on the floor, ran to his 2
children, took them into his arms, and ran outside. He afterwards said he believed that the house was on fire.14 A father
took his baby girl from her cradle, brought her into the attic
and tied her, while dreaming that officials from child welfare wanted to deprive him of the custody of the baby.16
These cases illustrate that a complex mental content can be syn�
chronous with elaborate motor behavior erupting from SWS, sug�
gesting a mind-behavior isomorphism. One may notice, however,
that the patients reported at least 1 dreamlike mentation associated
with a sleepwalking/sleep terrors episode. They could not be pre�
cise enough to determine how many sleepwalking/sleep terrors
episodes were associated with dreamlike mentations, as they were
frequently amnesic of numerous episodes. In this study, we did
DISCUSSION
In this group of 43 adults with sleepwalking/sleep terrors, as
many as 71% of patients reported at least ������������������
1�����������������
dreamlike menta�
tion associated with a nocturnal motor episode. The dreamlike
mentations were mostly short and frequently unpleasant. There
was no major difference regarding the frequency and nature of
the dreamlike mentation content in sleepwalkers compared with
patients with sleep terrors. Compared with healthy controls,
the patients with sleepwalking/sleep terrors had more frequent
arousals from SWS (despite a similar percentage of SWS) and
reported more severe daytime sleepiness.
SLEEP, Vol. 32, No. 12, 2009
She ran out of her bed, rubbed her hair,
and saw the cockroach and needed time
to realize that she was in the dark without
any insects.
He climbed onto the roof of the house.
1624
Dreamlike Mentations and Sleep Terrors in Adults—Oudiette et al
not systematically interview the patient spouse,
Table 3—Sleep Measures in Patients with NREM Sleep Parasomnia and Controls
who could possibly recall many more episodes
than the patient. All in all, dreamlike mentation
Patients
Controls
recalls were occasionally associated with sleep�
Number
43
25
walking/sleep terrors, but the exact frequency of
Nighttime sleep
this association is still unknown.
Total sleep period, min
522 ± 82
543 ± 73
The mental content associated with sleepwalk�
Total sleep time, min
460 ± 76
491 ± 78
ing/sleep terrors in our patients was mostly short
Sleep efficiency, %
88 ± 8
90 ± 6
and contained 1�������������������������������
��������������������������������
single scene, except for 5 pa�
Latency to sleep onset, min
28 ± 21
30 ± 23
tients (Patients 4, 15, 21, 18, and 1 child climbing
Sleep duration, min
on the roof as he followed a long and movie-like
Stage 1
21 ± 12 (4.6%)
19 ± 12 (3.9%)
inner scenario). This scene was visual. Similar to
Stage 2
221 ± 56 (47.9%)
242 ± 55 (47.5%)
our patients, a patient with sleepwalking/sleep
Stage 3-4
117 ± 33 (25.7%)
123 ± 28 (25.3%)
terrors in another series attempted to flee or fight
REM sleep
107 ± 54 (21.7%)
105 ± 37 (21.0%)
in self-defense during the night because he felt
Sleep fragmentation
threatened or attacked by individuals with “blank
Periodic leg movements index
4.6 ± 5.1
3.4 ± 11.7
eyes” and by a cow with a knife hidden in its
Apnea-hypopnea index
3.4 ± 6.9
2.0 ± 2.7
mouth as a tongue.13 One may discuss whether
Arousals index
14.0 ± 9.2
15.5 ± 5.1
these brief scenes are closer to a hypnagogic hal�
Number of arousals from SWS
4.8 ± 3.0*
1.2 ± 1.0
lucination from SWS than a more classic dream.
Epworth Sleepiness Scale score
10 ± 4
Patient 9 (video) opened her eyes and turned her
Percentage of patients with a score > than 10
47
0
head, while still in quiet SWS and then dread�
NREM refers to non-rapid eye movement sleep; REM, rapid eye movement sleep; SWS, slow
fully screamed. She behaved as somebody dis�
wave
sleep.
covering a frightening scene. These brief, visual,
mental contents during sleepwalking/sleep ter�
rors suggest that the episodes could be either the terminal part
with nonviolent sleepwalking/sleep terrors are less likely to
of a longer dream forgotten at time of arousal or a phasic, short,
seek medical advice. There could be a bias in our series towards
mental creation elicited before or just at the time of arousal. One
violent, unpleasant, or more disturbing cases. The association
may wonder if these phasic visions could be triggered by ponto�
of a dreamlike mentation (or a nightmare) recall with violent
geniculooccipital waves that occur as rare isolated events during
frightened behavior in sleepwalkers suggests that the distinc�
SWS in cats, whereas they are numerous and grouped in bursts
tion between sleepwalking and RBD can be difficult when it is
during REM sleep.25 Some authors have proposed that sleepwalk�
based only on a sleep interview. Confusion during an interview
ing/sleep terrors episodes are triggered by accelerated heart and
could lead to the misclassification of nocturnal violence during
respiratory rates occurring during the arousal state rather than by
epidemiologic surveys29 or case-reports.30 Some elements in the
20
the mental activity preceding the arousal state. Patient 9 here,
interview may however direct the clinician toward a diagnosis
however, does not fit the model, as she quietly opened her eyes
of sleepwalking rather than RBD. They include the age (young
with a normal heart rate before screaming.
in NREM parasomnias, middle-aged or old in patients with
The subject of scenes associated with sleepwalking/sleep ter�
RBD), the occurrence of walking (frequent in NREM parasom�
rors is mostly frightening, to the point that many patients call
nias, exceptional in RBD),31 the frequency (low in patients with
them nightmares in our clinical experience. As many as 54%
NREM parasomnias, high in patients with RBD), and nature
of the reports contained elements of misfortune (whereas none
(a single brief scene in NREM parasomnias vs a long detailed
contained fortune), 24% were aggressive, and 84% were appre�
dream in RBD) of the dreamlike mentation associated with the
hensive. In addition, 4 patients had “blank” dreams (the feeling
behavior and, to some extent, its content. In our study, sleep�
of having dreamt before arousal but with no recall) associated
walkers report misfortune, whereas patients with RBD report
with a pure intense fear. The strongly negative emotions associ�
aggression.32 Misfortune is defined by any injury, mishap, or
ated with sleepwalking/sleep terrors suggest that the emotional
adversity occurring to a character through chance or environ�
network, and especially the amygdala, would be activated during
mental circumstances (e.g., collapsing ceiling) over which it
the event. A single functional imaging session in a sleepwalker
was impossible to exert personal control.23 In most dreamlike
showed that the posterior cingulate cortex (which is part of the
mentations reported by patients with RBD and pseudo-RBD as�
emotional processing network) and the anterior cerebellum are
sociated with severe obstructive sleep apnea syndrome,33 the
activated during sleepwalking, whereas the frontoparietal corti�
dreamers (or their loved ones) are a victim of an aggression
ces are deactivated.26 Whether patients with sleepwalking/sleep
(attack, rape, theft) by a human or an animal and fight back.32,34
terrors exhibit an abnormal processing of emotion, even during
There is, however, possible an overlap between the contents of
the daytime, as was recently shown in patients with narcolepsy/
dreamlike mentations in NREM parasomnia and RBD, so that a
cataplexy, should be determined.27
videopolysomnography will be helpful in doubtful cases.
Some sleepwalkers in our series, however, experienced not
This study confirms previous observations that sudden
only misfortune, but also sang dirty or childish songs and qui�
arousals from SWS are frequent in patients with sleepwalking/
etly spoke while asleep. Similar to the previous report of non�
sleep terrors and shows that the arousals are 4�����������������
���������������
times more com�
violent behaviors during RBD,28 one may imagine that people
mon than in healthy control subjects. Half of the patients with
SLEEP, Vol. 32, No. 12, 2009
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Dreamlike Mentations and Sleep Terrors in Adults—Oudiette et al
sleepwalking/sleep terrors reported abnormal levels of daytime
sleepiness. Sleepiness as a symptom of sleepwalking/sleep ter�
rors has not been previously specifically highlighted. Because
there is no difference other than the arousals from SWS between
the patients’ and control subjects’ sleep structures (especially
no more respiratory events during stage 4 sleep), we wonder
whether long confused arousals from stage 4 sleep would not
affect the restorative properties of sleep.
These data should be considered with a number of important
limitations. Sleep terrors and sleepwalking are usually described
as 2 distinct parasomnias. They are pooled here, which can be
considered as a limitation. They indeed show considerable over�
lap, as 70% patients here have sleep terrors and sleepwalking at
different periods of the night or the year or as a terror first (scream)
followed by an attempt to flee out of the bed. Frightening images
are not specific to sleep terrors (or sleep terrors/sleepwalking),
however, as they occurred here in 2 patients with isolated sleep�
walking. This result is observed in a small subsample, but it fur�
ther suggests that the boundary between sleepwalking and sleep
terrors is very thin. Another limitation in our study is that the
dreamlike mentations have been gathered retrospectively, over a
lifetime span, so that recall bias is possible. All studies on dreams
are by definition retrospective, as the subject cannot at the same
time experience the dream and report it to someone else. It is
probable, however, that the time elapsed between the dreamlike
mentation experience and the report alters the memory of the
dreamlike mentation, so that an immediate recall would further
enhance the percentage and the length of dreamlike mentations
reported by our patients, as it is the case in normal subjects. This
bias would underestimate (and not overestimate) the frequency
of dreamlike mentations in our study. Also, healthy subjects tend
to remember more easily the dreamlike mentations with strik�
ing rather than ordinary content.35 To avoid this bias, one should
perform a systematic, nightly based interview after each NREM
parasomnia in a series of patients, which would be a costly but
fascinating future study. Notably, because none of our 43 pa�
tients had any dreamlike mentation recall the next morning in the
sleep-unit settings, such a large study may require either home
monitoring, staying a week in the sleep unit, or using provocative
methods to increase the number of parasomnia events.
In conclusion, dreamlike mentations (mostly brief, frighten�
ing visual images) may occasionally exist during sleepwalking
and sleep terrors, suggesting that a complex mental activity
takes place during SWS. Sleepwalking may thus represent act�
ing out of the corresponding dreamlike mentations. A previous
study proposed that awakening serves as an indirect measure
of nightmare intensity, the emotions during nightmares being
more intense than during bad dreams.36 Similarly, the emotional
character of the frightening image could be 1 of the proximal
trigger of the sleepwalking and sleep terror.
and has participated in speaking engagements for UCB. The
other authors have indicated no financial conflicts of interest.
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This study was in part supported by a grant form FRC 2007
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Disclosure Statement
This was not an industry supported study. Dr. Arnulf has
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APPENDIX
Case Report
A
Patient 21 was a 23-year-old
1
employee in a school who had ex�
R
perienced severe sleepwalking
2
and sleep terrors for 16 years. Her
grandfather was a sleepwalker (he
3
jumped through the window into
4
a rosebush when he was young),
and her mother still talks and walks
while asleep. The patient had no
20:33
22:00
00:00
02:00
04:00
06:00
history of depression or psychologi�
cal trauma. She had frequent night�
Figure 1—Hypnogram of Patient 21 (case report) with 10 sudden awakenings from slow wave sleep (shown
mares, several times per night, but
by arrows) with corresponding behavior of surprise, sitting, and talking evoking a “status parasomnicus.”
they occurred in clusters for several
days or weeks at a time and then
disappeared for several weeks. Fa�
tions, she had to do something to survive. For example, she had
tigue, stress, changes in altitude, and horror films precipitated
to stay under the duvet because a superior power ordered it, she
the episodes. She had fewer episodes during the holidays and
had to wash her feet in the bathroom, and she had to plug the
when she did not sleep at home. She complained of daytime
bathroom door with clothes. Once, she saw her aggressor as a
sleepiness, with an Epworth Sleepiness Scale score of 14. She
Chinese dragon. In a recurrent dreamlike mentation, she was
hurt herself several times during the sleepwalking episodes, in�
in a large white room with many Smarties (colored chocolate
cluding a broken clavicle, a twisted ankle, a head injury, and an
candies) on the floor. She had to sort and pile them up accord�
ear wound. During the nighttime videopolysomnography, the
ing to their colors, but the stack always fell and she had to start
sleep architecture was normal (without epileptiform activity),
again. She required several minutes after awakening to admit
except for 10 sudden awakenings from non-rapid eye move�
that nothing bad had happened. When she resumed sleep, she
ment sleep stage 4 (Figure 1). During these awakenings, she
experienced the same dreamlike mentation again. She also ex�
opened the eyes and looked, with a scared expression, around
perienced dreamlike mentations resembling horror films (“the
her. She sat twice on the bed and spoke shortly. At home dur�
living-dead type”). She saw dead heads falling, people hanged
ing the sleepwalking episodes, she was agile, opening doors,
in her room, acid falling from the roof, thieves, killers, and
and avoiding routine obstacles. Only unforeseeable obstacles,
children from her school slaughtered by a madman. When she
such as a bag left unattended on the floor the previous evening,
had these types of dreamlike mentations, she screamed (wak�
would cause her to fall. If someone awoke her at that time, she
ing up her neighborhood), ran to the bathroom, and locked the
would have superhuman strength and be very aggressive to�
door. In addition, she had a recurrent dreamlike mentation in
ward the intruder. She reported vivid mental imagery during the
which a gorilla came into her house, grabbed her by the hair,
sleepwalking episodes. She experienced recurrent nightmares
and dragged her down the stairs. During this dreamlike menta�
with short scenarios including floods, collapsing buildings,
tion, she was partly aware but could not refrain from screaming
fires, and 2 walls getting closer to the point of crushing her.
and taking part in her dreamlike mentation, while she simulta�
In these cases, she had to escape and felt extreme apprehen�
neously thought “Oh no, not the gorilla again!” Her dreamlike
sion. She shouted loudly, ran away from the bed, and hid in the
mentation could also be influenced by daytime context. During
bathroom or under the living room table. She was able to dress
the rugby world cup 2007 in Paris, she dreamt that an army of
within a few seconds to get out of the apartment and hurtle
rugbymen wanted to kill her. Of note, she also had good dreams
down the stairs before being aware that it was just a nightmare.
but did not remember a sleepwalking episode associated with
She also experienced other types of mental content, that she
good dreams, nor did her boyfriend report such occurrences.
herself called “the mission dreams.” In these dreamlike menta�
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Dreamlike Mentations and Sleep Terrors in Adults—Oudiette et al